Cubeb

What is Cubeb?

Cubeb is the dried, unripe fruit of Piper cubeba L.f., a Piperaceae climber named by the younger Linnaeus in 1782, and the plant the Chinese Pharmacopoeia calls the cubeb berry is not it. Cheng and colleagues at Zhejiang University wrote in Molecules in 2018 that Litsea cubeba, a laurel in the Lauraceae, "has been described as the cubeb berry in the Chinese Pharmacopoeia," while Piper cubeba "has been also listed as the origin of cubeb berries." Two plants from two families share one trade name, and in China the one with pharmacopeial standing is the laurel.

The Piper fruit is a 4 to 6 mm blackish-gray globe on a stalk of its own length, which is why the spice is also called tailed pepper. It is harvested green, dried and sold whole, and the stalk is the quickest field check that a buyer is looking at Piper cubeba and not a black peppercorn. Plants of the World Online (taxon 681071-1) gives the native range as Indo-China to Malesia and lists Borneo, Cambodia, the Lesser Sunda Islands, Malaya, Maluku, Myanmar, Sulawesi, Sumatra and Vietnam. Java, the island the trade has always associated with cubeb and the island John Crawfurd in 1818 said was its only source, is not on Kew's native list. PROSEA, the Southeast Asian plant resource handbook, disagrees and calls the species a native of Java, Sumatra and Kalimantan. The two authorities agree that Java is where it is grown; they do not agree on whether it started there.

Common Names

• Cubeb, cubebs, tailed pepper, Java pepper, cubeb pepper

• Kabab chini, sheetal chini, kababchini (Hindi, Urdu, Bengali)

• Kemukus (Javanese; Crawfurd spelled it Cumucus in 1818)

• Cubeba, Cubebae fructus, the pharmacopeial Latin for the dried fruit

• Bi cheng qie (Chinese), the name that in the Chinese Pharmacopoeia points to Litsea cubeba

Primary Active Compounds

• (-)-Cubebin, a dibenzylbutyrolactol lignan, reported at about 2.5 percent of the fruit by Schmidt in the nineteenth century and "to the extent of 3 percent" in Godoy de Lima's 2018 review

• (-)-Hinokinin, the oxidized form of cubebin, plus yatein, clusin, dihydroclusin and dihydrocubebin, the methylenedioxyphenyl lignans that inactivate CYP3A4

• Sesquiterpenes: alpha-cubebene, beta-cubebene, cubebol, alpha-copaene, delta-cadinene and germacrene D, the fraction that defines a genuine cubeb oil

• Sabinene, the monoterpene that leads the classic reference oils at 9.1 to 28.09 percent

• Cubebic acid, about 1 to 1.7 percent, the compound behind the crimson sulfuric acid identity test

• Piperine, present but belonging to a different story and a different issue

Key Note

The British Pharmaceutical Codex of 1911 put the volatile oil content of genuine cubebs at 10 to 18 percent, and PROSEA's monograph says about 10 to 20 percent. Three recent peer-reviewed hydrodistillations of material bought or collected as cubeb yielded 1.0 percent (Saudi market, 2020), 1.11 percent (Indonesian market, authenticated, 2019) and 1.9 percent (Morocco, 2024). The oil fraction is the cheapest thing in this fruit to measure and the first to disappear when the fruit is old, over-dried or not cubeb.

Cubeb is a spice with one real pharmacological signal, a drug-metabolism interaction, and a marketing story that ended in the 1940s.

Primary Functions & Benefits

Cubeb has no established clinical function. It has a well-characterized chemistry with three documented effects, two of them in cells and one of them in a 30-person trial that 13 people finished.

CYP3A4 inactivation

The strongest and best-replicated finding is a drug-metabolism effect. Usia and colleagues at Toyama Medical and Pharmaceutical University screened 30 Indonesian medicinal plants against human liver microsomes in 2005 and found the ethyl acetate fraction of a cubeb water extract inhibited CYP3A4-mediated erythromycin metabolism by 75.0 percent. Activity-guided isolation (Journal of Natural Products 2005;68:64) traced it to lignans with a methylenedioxyphenyl ring: (8R,8'R,9'S)-5-methoxyclusin, (-)-clusin, (-)-yatein, ethoxyclusin and (-)-dihydroclusin, with IC50 values of 0.44 to 1.0 micromolar against a ketoconazole control of 0.72 micromolar. A companion paper (Life Sciences 2005;76:2381) showed the inhibition was time-, concentration- and NADPH-dependent, with inactivation constants of 0.054 to 0.373 micromolar and a 455 nm spectral peak characteristic of a metabolite-intermediate complex. That is the signature of mechanism-based inactivation: the enzyme is destroyed, not merely occupied, and recovers only as new enzyme is synthesized. For a supplement buyer it is a hazard, covered in Interactions.

Antimicrobial activity in vitro

Silva and colleagues (Phytotherapy Research 2007;21:420) found the crude ethanol extract of cubeb seed inhibited Streptococcus salivarius at 80 micrograms per mL, and isolated (-)-cubebin had MIC values of 0.20 to 0.35 millimolar against oral streptococci and Enterococcus faecalis. Hinokinin was fungicidal against Candida albicans at 0.28 millimolar. Alqadeeri and colleagues (Molecules 2019;24:3095) isolated beta-asarone and asaronaldehyde from the dichloromethane fraction of a methanol extract of Central Java berries authenticated at Herbarium Bandungense (voucher HBG10PC01), both compounds for the first time from this plant, with MICs of 63.0 to 125.0 micrograms per mL against four Bacillus strains and complete spore kill at 0.1 percent within one to four hours depending on the strain. None of this has been tested in an infected human.

One small kidney trial

Jahan and colleagues (Avicenna Journal of Medical Biochemistry 2023;11:46) randomized 30 adults with stage 1 to 3 chronic kidney disease, mean age 56.20 years and 25 of them men, to powdered cubeb fruit in capsules (two capsules three times daily, about 4 g per day) or a polyherbal syrup for 42 days, open-label. In the cubeb arm serum creatinine fell from 2.09 to 1.75 mg/dL (P = 0.028) and estimated GFR rose from 42.84 to 51.59 (P = 0.015). Blood urea did not change (48.33 to 49.73). The comparator arm's eGFR also rose significantly, from 43.38 to 48.87 (P = 0.012). The authors report the between-group difference as favoring cubeb (eGFR P = 0.001, creatinine P = 0.013), and the number that undercuts that result is in their own flow diagram: 8 of the 15 cubeb patients and 9 of the 15 controls were lost to follow-up, and the analysis carried each dropout's last value forward. Seven people finished six weeks on cubeb. Fifteen randomized per arm, no placebo, no blinding, more than half the cohort gone before the end.

Forms & Standardization

No cubeb supplement the author could find is standardized to anything. The detail is where a buyer can act.

Whole and powdered dried fruit

The spice form. The USP description quoted in King's 1898 Dispensatory gives the official article as the unripe fruit, "globular, about 4 or 6 Mm. in diameter," on a stipe of 6 or 8 mm, "blackish-gray, internally whitish and hollow," and specified that the stalks should not be mixed in. The 1911 BPC added that the drug "should not contain the rachis of the inflorescence" or "too many immature fruits." Whole fruit is the only form in which the stalk, the one visual identity feature, survives. Powder removes it. Capsules of powder are what the 2023 kidney trial used and what the Unani classical dose cited by Bano and colleagues (Integrative Medicine Research 2018) refers to; both figures sit in Special Considerations, scoped to the settings they came from.

Tincture and glycerite

A representative retail listing (Herbal Terra, cubeb dried fruit tincture, $19.95 for 2 fl oz) names the species, the plant part and a menstruum of organic cane alcohol, water and vegetable glycerin. It gives no extraction ratio, no alcohol percentage and no marker compound. The suggested use is 20 to 30 drops, about 1 mL, up to four times daily. The historical tincture it descends from was defined: the BPC 1911 Tinctura Cubebae was 20 parts powdered cubebs percolated to 100 parts with alcohol, a stated 1:5 ratio. A modern label that omits the ratio has told you less than a 1911 one did.

Essential oil

Hydrodistilled from the crushed fruit, pale greenish-yellow to bluish-yellow by PROSEA's description, and the only form with a published chemical fingerprint. An authentic oil is sesquiterpene-rich. Shankaracharya's 1995 Indian analysis gave sabinene 28.09 percent, cubebol 15.18 percent, beta-cubebene 4.39 percent, alpha-copaene 4.01 percent and germacrene D 2.89 percent. Bos and colleagues' 2007 oil, as reported by Andriana, ran beta-elemene 9.4 percent and sabinene 9.1 percent. Cubeb oil is a flavoring, not a supplement: PROSEA records it as GRAS under FEMA number 2339 at a maximum of about 0.004 percent in food and up to 0.8 percent in soaps and perfumery.

Oleoresin

Solvent-extracted, used to flavor spice blends and tobacco. The volatile-compound table in Drissi's 2022 review lists cubebol at 26.1 percent in its oleoresin column against 4.7 percent in its essential oil column. The table pools several sources, so the two columns are not one lot analyzed two ways, but the direction is what solvent extraction predicts: the less volatile sesquiterpene alcohol concentrates when the monoterpenes are not carried over by steam.

Cubebol, the one standardized derivative

Firmenich SA of Geneva held the one cubeb-derived product with a specification. US patent 6,214,788, filed March 28, 2000 on a Swiss priority of March 31, 1999 and granted April 10, 2001, claims (-)-cubebol as a cooling and refreshing flavor ingredient in chewing gum, beverages, ice cream, toothpaste and tobacco, with cubeb oil enriched to at least 50 percent cubebol and epi-cubebol, which is "very bitter," held under 5 percent. The specification describes a commercial oil at 37 percent cubebol fractionated to 88 percent. Its 20-year term ran out on March 28, 2020. This is the industrial meaning of "cubeb"; it has nothing to do with capsules.

The lignan assay that exists and nobody uses

Arruda and colleagues at the University of São Paulo (Journal of Agricultural and Food Chemistry 2019;67:753) validated a reverse-phase HPLC method to ANVISA and ICH guidelines for five cubeb lignans, (+)-dihydroclusin, (-)-clusin, (-)-cubebin, (-)-yatein and (-)-haplomyrfolin, and optimized extraction to ultrasound in 84 percent aqueous ethanol for 38 minutes, which recovers more than 80 percent of the total lignans in one pass. A product could state its cubebin content in milligrams per capsule by this method. The author has found none that does.

Food Sources

Cubeb is a spice, and the spice route is how most people have ever consumed it.

Where it is eaten

Drissi's 2022 review places it in Moroccan cooking and in ras el hanout, the North African blend. Bombay Sapphire lists "cubeb berries from Java" among its ten gin botanicals. The 1818 Edinburgh report already noted that cubeb was "given to public singers at theatres to clear the voice." In the United States, 21 CFR 172.510 lists cubeb, Piper cubeba L.f., as a natural flavoring substance with no limitation beyond the minimum quantity needed for the flavoring effect under good manufacturing practice. The safrole-free condition that the same table attaches to sassafras leaves is not attached to cubeb.

What a culinary dose delivers

A spice-level use is a few fruits in a pot. Against a fruit with 2.5 to 3 percent cubebin and 10 to 18 percent volatile oil (by the historical specifications), a 100 mg pinch carries 2.5 to 3 mg of cubebin and 10 to 18 mg of oil. The 2023 trial's capsule regimen was 40 times that. No published study has measured cubebin in human blood after either, and the Drissi review states flatly that "there is no yet systemic data regarding the pharmacokinetics" of the plant.

Nutrients, with a caveat

Drissi's 2024 analysis of the Moroccan berries reported iron at 64.75 mg/kg, sodium at 161.67 mg/kg, zinc at 4.69 mg/kg, calcium at 0.71 percent and potassium at 1.50 percent. At a 100 mg culinary dose that is 6.5 micrograms of iron, or 0.04 percent of the 18 mg daily allowance for a woman aged 19 to 50. The caveat is Section 2: the oil from the same batch was 76.99 percent Z-isoeugenol and contained no cubebene, so these numbers describe whatever was harvested near Berkane rather than, with any confidence, Piper cubeba.

Eat the spice if you like the taste; there is no nutritional reason to.

Who Should Take Cubeb

As a spice, anyone who wants to. As a supplement, no group has been shown to benefit, so this section is short.

People for whom a trial exists

Adults with stage 1 to 3 chronic kidney disease are the only population with a controlled human study, and that study (Jahan 2023, n = 30 randomized, 13 completing, open-label, 42 days) rests on seven people who finished the cubeb arm, with both arms improving. Anyone with CKD is also the group most exposed to the CYP3A4 problem, since tacrolimus, cyclosporine, amlodipine and nifedipine are all CYP3A4 substrates. A kidney patient considering cubeb should raise it with the nephrologist managing those drugs, not decide alone.

People with a cultural or culinary reason

In Unani practice in India, kabab chini is a classical medicine with a stated dose in the gram range, used for urinary complaints, and in Javanese tradition, per Crawfurd's 1818 account, it was used "in some diseases of children, but never in gonorrhoea." Someone using it inside one of those traditions has a context. Someone who found it on a website selling the nineteenth-century European indication does not.

Who gains nothing

Anyone seeking the urinary antiseptic effect that drove 1818 to 1940 prescribing. That indication was a bacterial infection with a single-injection cure, and PubMed indexes no clinical trial of cubeb against the organism as of October 2026.

Who Should AVOID or Use Caution

Contraindications

• Anyone taking a drug whose dose depends on CYP3A4 and whose margin is narrow: tacrolimus, cyclosporine, sirolimus, simvastatin, lovastatin, midazolam, triazolam, apixaban, rivaroxaban. The cubeb lignans inactivate the enzyme rather than block it, so the effect outlasts the dose. See Interactions.

• Pregnancy and breastfeeding. The author found no reproductive toxicity data for the fruit, the lignans or the oil, and the Herbal Terra label itself states "Not for use during pregnancy or while breastfeeding."

• Children. The only pediatric use the author found is a croup regimen of cubeb oleoresin quoted in King's 1898 Dispensatory from a French physician, in an era before antibiotics (the figure is in Special Considerations, as history). Nothing supports it today.

• Anyone with a known allergy to Piper species.

Use Caution

• Kidney or urinary tract disease. The one retail label reviewed warns against use with "kidney or urinary-tract disease," the opposite of the indication under which the same product is marketed elsewhere. The 2023 trial in CKD reported no adverse events, but only 7 of the 15 people assigned to cubeb completed the six weeks, which is too few people for too short a time to establish safety in a damaged kidney.

• Gastric or duodenal ulcer and reflux. Also on the label, and consistent with a pungent Piper fruit.

• Hormone-sensitive conditions. Yam and colleagues at University Hospital Basel (Planta Medica 2007;74:33 and 2008;74:142) showed an ethanolic extract, P9605, inhibited 5-alpha-reductase II, antagonized the androgen receptor, inhibited aromatase and bound both estrogen receptors in vitro. None of this has been tested in a person, in either direction, which is why someone on tamoxifen, an aromatase inhibitor, finasteride or hormone replacement should not add an unquantified extract.

• Scheduled surgery. CYP3A4 inactivation affects midazolam, fentanyl and alfentanil. Stop two weeks before.

Critical Safety Point

The compounds behind cubeb's most reliable effect are the ones that make it dangerous with common prescriptions. Five cubeb lignans inhibited CYP3A4 at IC50 values of 0.44 to 1.0 micromolar, the same range as ketoconazole at 0.72, and ketoconazole is a prescription drug whose label carries a boxed warning that includes its drug interactions. A supplement bottle carries no such warning.

Recommended Dosages

There is no dose of cubeb that any regulator, pharmacopeia or clinical body currently recommends for any purpose. The only modern gram figures that exist belong to a supervised hospital trial and to a classical Unani text, and both are described where they belong, in Primary Functions and Special Considerations, not here. Nothing below is a target.

Powdered fruit, capsules

No amount has been shown to do anything in a person outside a nephrologist-monitored protocol in which more than half the participants dropped out. A capsule label that prints a milligram figure did not derive it from a human outcome.

Tincture

Retail labels suggest 20 to 30 drops, about 1 mL, up to four times daily, in 2 oz of water. Without a stated extraction ratio or alcohol percentage, 1 mL cannot be converted into milligrams of fruit, so the figure has no pharmacological content.

Essential oil

Not for internal use as a supplement. The oil's only regulated internal route is as a food flavoring at trace levels, about 0.004 percent per PROSEA's GRAS citation.

Duration

The longest human exposure with any monitoring is 42 days. The 90-day rodent data Drissi's review cites are for a related Piper species in mice, not this one. Anyone running past six weeks is past the evidence.

Timing & Administration

Nothing in the human record speaks to timing. The 2023 trial dosed after meals, three times daily, which is a convention for pungent spices rather than a pharmacokinetic finding. The lignans are lipophilic, and Arruda's optimized extraction solvent was 84 percent ethanol, which suggests food fat and alcohol increase what dissolves out of a capsule; no human absorption study confirms it.

The one timing fact that matters is pharmacological. Mechanism-based CYP3A4 inactivation does not clear when the inhibitor does; the enzyme has to be resynthesized, which takes days. Taking cubeb "away from" a medication does not avoid the interaction. Stopping it does, after a lag.

Timeline of Effects

There is one human timeline, and it belongs to a supervised trial rather than to a supplement user.

What was measured, and when

Jahan's 2023 protocol tabulated laboratory values at baseline, week 3 and week 6, with weekly visits in between. The creatinine change in the cubeb arm, 2.09 to 1.75 mg/dL, most of it already present at week 3 (1.76), is the entire kinetic record of this plant in humans, and it was recorded in an arm that lost 8 of 15 people along the way. No published study has measured onset or washout, and none has followed anyone past six weeks.

What the enzyme timeline looks like

The CYP3A4 effect has a kinetic profile from the microsome data: kinact of 0.225 to 0.320 per minute means half of the exposed enzyme is inactivated within two to three minutes at saturating concentration. Whether a capsule reaches the liver at a concentration that matters is unknown, because no published study has measured plasma clusin or yatein after oral cubeb.

A fair trial

There is no trial length after which "it is not working" can be concluded, because no endpoint has been shown to move. The rule runs the other way: six weeks is the longest exposure with any safety monitoring, so six weeks is where a user has outrun the data, not where a result is due.

Benefits of Taking Cubeb

Documented, in humans

A fall in serum creatinine of 0.34 mg/dL and a rise in eGFR of 8.75 units over 42 days in an arm of 15 people with early kidney disease, of whom 8 were lost to follow-up and had their last values carried forward, in an open-label trial whose comparator arm also improved. A 2024 open-label Unani study (Qureshi, see Research Status) used cubeb as one of seven herbs in a 500 mg capsule, so nothing in it can be assigned to cubeb. That is the complete list.

Documented, in animals

Bano and colleagues (Integrative Medicine Research 2018;7:358) gave a 50 percent ethanol Soxhlet extract at 35 and 60 mg/kg to male Sprague Dawley rats with ethylene glycol and ammonium chloride-induced calcium oxalate urolithiasis for 14 days. Urinary crystals fell significantly, urinary magnesium rose, and serum creatinine and urea fell compared with disease controls. The extract yield was 10.05 percent; the authors derived the 35 mg/kg extract dose from a 3 g Unani human dose by a conversion factor of 7 (350 mg/kg of crude fruit for a rat) and set the 60 mg/kg dose by the Miller and Tainter method. A rat model of chemically forced stone formation is not a human with a stone.

Esperandim and colleagues gave cubebins and hinokinins orally and intraperitoneally at 20 and 50 mg/kg to BALB/c mice in the chronic phase of Trypanosoma cruzi infection and reported, per the Godoy de Lima review, a greater reduction in parasitism than benznidazole, the standard Chagas drug, in all organs assessed (2010); a 2013 acute-phase study found a significant reduction against untreated controls. The lignans and their derivatives are the subject of a US patent (7,521,569) on that basis. It is a drug development lead, not a supplement benefit.

Documented, in cells

Cubebin's cytotoxicity against lung (A549), leukemia (K562) and nasopharyngeal (KB) cancer lines below 9 micromolar; hinokinin's inhibition of IL-6 at 20.5 micromolar; the Basel group's antiandrogen and antiestrogen findings; vasorelaxation of rat aortic rings via nitric oxide. Each is a dish result on an isolated compound at a concentration no capsule has been shown to produce in blood.

Marketed, undocumented

Urinary antiseptic, aphrodisiac, respiratory tonic; PROSEA lists the last two among traditional Javanese uses. The first is the 1818 indication, closed since the 1940s. The other two have no human study.

Potential Negatives & Side Effects

From the human record

The 2023 trial reported no adverse events and safety parameters (liver enzymes, blood counts, ESR) within normal limits, in the 7 of 15 cubeb patients who completed 42 days; the paper gives no values and does not say why the other 8 left. Crawfurd's 1818 report, at the far larger dose of a dessert spoonful five or six times a day, recorded "a slight purging," a distinctive odor imparted to the urine, increased urine volume, occasional facial flushing and "a burning heat in the palms of the hands and soles of the feet." The Edinburgh editor's single case developed "swelled testicle," which is a complication of the untreated infection rather than of the pepper, and which the 1818 authors could not have distinguished.

From the chemistry

• Histamine release. Ikawati and colleagues, cited in Drissi's review, found hexane and ethanol extracts caused lysis of 2H3 basophil-type cells with histamine release comparable to thapsigargin. In a dish, that is a mechanism for flushing. In a person it has not been studied.

• Dopamine and norepinephrine transporter inhibition. Timple and colleagues (2013) found (-)-hinokinin selectively and noncompetitively inhibited both transporters in vitro with low affinity for the serotonin transporter. Relevance at supplement doses is unknown.

• Cytotoxicity at high concentration. Niwa and colleagues found (-)-cubebin cytotoxic to HT29 colon cells at 280 micromolar, with no cytotoxicity, mutagenicity or altered growth kinetics at or below 28 micromolar.

• Methyleugenol and beta-asarone. Both have been isolated from material sold as cubeb, and both are rodent carcinogens; see Toxicity.

Allergy

Piper fruits are not a recognized common allergen. Mouth or skin irritation from the pungent fruit is the realistic reaction.

Deficiency Symptoms

What cubeb addresses

Nothing. Cubeb is a spice; the human body does not make, store or require any compound in it. No cubebin, hinokinin or cubebene has a physiological role, a plasma reference range or a deficiency state.

Bottom line

A reader who feels worse without cubeb is not deficient in cubeb. If the reason was a urinary symptom, that symptom has a diagnosis and a treatment, and neither involves this fruit.

Toxicity Symptoms

At high intake

The author found no modern report of human overdose. In rats, Drissi's review records a methanol fruit extract without toxicity or death at 2,000 mg/kg, and the essential oil without mortality or behavioral change from 50 to 3,000 mg/kg in male Wistar rats. The 1818 dose, three drachms of powder five or six times daily, roughly 60 to 70 g of fruit a day, produced purging and flushing but no recorded serious harm in the cases Crawfurd described. Acute poisoning from the fruit is not what this section is about.

The carcinogens that can ride along

Methyleugenol was listed as "reasonably anticipated to be a human carcinogen" in the Tenth Report on Carcinogens in 2002 on the strength of NTP Technical Report 491, in which oral dosing produced liver tumors in both sexes of F344/N rats and B6C3F1 mice and stomach neuroendocrine tumors in rats. The NTP profile notes it was detected in 98 percent of 206 NHANES III serum samples. The Saudi market "cubeb" oil was 41.31 percent methyleugenol. Beta-asarone is the compound for which FDA prohibited calamus, its oil and its extract from food in an order of May 9, 1968, now codified at 21 CFR 189.110. Alqadeeri isolated it in 2019 from herbarium-authenticated Javanese cubeb, not from a substitute, so authenticity does not rule it out. Neither compound has a measured level in any cubeb capsule, which is the point: a supplement that could be anything from authentic sesquiterpene-rich cubeb to a eugenol-type substitute has an unknown load of two compounds regulators treat as carcinogens.

Signs to reduce or stop

• New flushing, palmar burning or loose stools after starting, the 1818 signature

• Any change in effect or side effects of a prescription drug, particularly drowsiness on a benzodiazepine or sedative, muscle pain on a statin, or altered levels on a transplant drug

• Unexplained rise in liver enzymes on routine testing

• Any reaction at all in someone pregnant, who should not have started

General note

For this fruit the dose-related hazard is not the fruit but the drug taken alongside it. A toxicity section that stopped at LD50 would miss cubeb's only plausible route to a hospital.

How Cubeb Works

Cubeb's constituents work through two chemistries this issue owns, the lignans and the sesquiterpenes, and the first is far better understood than the second.

The lignan chemistry

Lignans are dimers of two phenylpropanoid units; Haworth coined the class name in 1936. In cubeb the pathway, as proposed by Pissurno and Laurentiz in 2017, runs from two coniferyl alcohol units through pinoresinol, lariciresinol and secoisolariciresinol to matairesinol, then closes the methylenedioxy bridges to give cubebin. Cubebin is a lactol, meaning the lactone ring carries a hemiacetal hydroxyl, and it exists as a mixture of epimers at C-9' that interconvert in solution because lactols open and close. That instability is why early structural work was confused (Davidson and colleagues' total synthesis showed a reported cubebin isomer was in fact a dimer, bicubebin B) and why cubebin is awkward as an analytical marker. Oxidation of the lactol gives hinokinin, the lactone. Godoy de Lima's review counts 24 lignans reported from cubeb extracts; Drissi's counts 28 from leaves, berries and stalks combined, with yatein, not cubebin, the most abundant in Indonesian berries in the study they cite. Twenty-four versus 28 is a difference in what was counted, not an error, but "cubebin content" and "lignan content" are different numbers and a label using either should say which.

The mechanism that matters pharmacologically is the methylenedioxyphenyl ring. CYP3A4 oxidizes the methylene carbon of that ring to a carbene that coordinates the heme iron, producing the 455 nm absorbance Usia observed and a complex the enzyme cannot shed. Every cubeb lignan tested with that ring (clusin, dihydroclusin, yatein, hinokinin, dihydrocubebin) did it, and the Journal of Natural Products paper attributes the potency specifically to compounds "having one methylenedioxyphenyl moiety in their structures." It is the same chemistry by which safrole, myristicin and the insecticide synergist piperonyl butoxide inactivate P450s; grapefruit's bergamottin reaches the same end by a different route.

The sesquiterpene chemistry

Cubeb's volatile fraction is dominated by sesquiterpenes, 15-carbon terpenes built from three isoprene units, and three of them carry the plant's name: alpha-cubebene and beta-cubebene (tricyclic hydrocarbons) and cubebol (a tricyclic alcohol). Cheng's 2018 work identified alpha-cubebene as the marker that separated Piper cubeba from Litsea cubeba in principal component analysis, present at only 0.4 to 0.52 percent but detected in every Piper extract and no Litsea extract. Alpha-copaene, delta-cadinene and germacrene D are the others that recur across authentic oils. The sesquiterpenes have no credited systemic pharmacology in humans; their documented actions are insecticidal (acetylcholinesterase inhibition in fumigated rice weevil, per Drissi) and sensory, the cooling of cubebol being the one Firmenich patented. What they offer a buyer is identity: an oil or extract with no cubebene and no cubebol is, on the published evidence, not cubeb.

What is not known

Whether any lignan reaches human plasma after an oral dose of fruit, and at what concentration. Every mechanism above is a mechanism of the compound, not yet of the supplement.

Synergistic Supplements

Nothing has been tested with cubeb in a human, so this section lists pairings a reader will meet and what the chemistry says.

• Black pepper or piperine. Marketed together as "pepper blends." Cubeb contains piperine itself, and the bioavailability story belongs to the published Curcumin issue. The point here is additive: piperine inhibits CYP3A4 and P-glycoprotein by its own route, and stacking it on a mechanism-based inactivator compounds an interaction, not a benefit.

• Grapefruit, bergamottin, goldenseal, St John's wort. The first three are CYP3A4 inhibitors; the last is an inducer. All change the same enzyme cubeb inactivates, in unpredictable net directions. Avoid rather than combine.

• Cranberry, D-mannose, uva ursi. The urinary "antiseptic" stack cubeb is sold into. No study of any combination exists. Uva ursi carries its own hydroquinone concern and belongs to its own issue.

• Saw palmetto, nettle root. The "prostate support" stack, built on the Basel in vitro findings. Untested together or alone for this purpose in humans.

A spice does not need a synergist, and a supplement with no demonstrated effect cannot have one.

Interactions & What NOT to Take

This section justifies the issue.

The mechanism, in one paragraph

Usia's 2005 Life Sciences paper established that five cubeb lignans are mechanism-based inactivators of human CYP3A4: inhibition increased with time and with NADPH, apparent Ki values ran 1.96 to 4.07 micromolar, inactivation constants KI ran 0.054 to 0.373 micromolar with kinact of 0.225 to 0.320 per minute, and clusin and dihydroclusin were the most potent at KI 0.082 and 0.054 micromolar. The spectral signature at 455 nm identified a metabolite-intermediate complex. A reversible inhibitor stops working when it leaves. An inactivator leaves behind a dead enzyme.

Drugs where this matters most

• Transplant immunosuppressants: tacrolimus, cyclosporine, sirolimus, everolimus. Narrow margin, CYP3A4-cleared, monitored by blood level. An unannounced rise is nephrotoxic.

• Statins cleared by CYP3A4: simvastatin, lovastatin, atorvastatin. The first two carry a label contraindication with strong inhibitors because of myopathy and rhabdomyolysis.

• Benzodiazepines and sedatives: midazolam, triazolam, alprazolam, zolpidem. Deeper and longer sedation.

• Anticoagulants: apixaban, rivaroxaban. Both CYP3A4 and P-glycoprotein substrates; more drug means more bleeding.

• Calcium channel blockers: amlodipine, nifedipine, felodipine. Hypotension.

• Opioids: fentanyl, oxycodone, methadone. Respiratory depression.

• Oncology drugs cleared by CYP3A4, where the prescriber has already said no to grapefruit. Cubeb belongs on the same list.

What the evidence does not show

No human pharmacokinetic interaction study has been done with cubeb and any drug. The whole case rests on microsomes and on the chemistry being identical to that of compounds (bergamottin from grapefruit, piperine from black pepper) that do interact in people. That is a strong inference, not a measurement. Understating it would be the more dangerous error.

What not to take it with

Any of the drugs above without telling the prescriber, any other CYP3A4 inhibitor, and any product whose label does not name the species and plant part, since an unidentified Piper or Litsea fruit is a different unknown.

Quality, Testing & Adulteration

The documented substitutes

PROSEA's monograph lists the fruits historically passed off as cubeb: within the genus, Piper baccatum, P. caninum, P. crassipes, P. guineense, P. mollissimum, P. nigrum and P. ribesioides; outside it, Bridelia tomentosa (Euphorbiaceae), Lindera species and Litsea cubeba (Lauraceae), Pericampylus glaucus (Menispermaceae), Rhamnus species, Xylopia frutescens (Annonaceae) and Zanthoxylum rhetsa (Rutaceae). Piper guineense travels under its own alias, "African cubeb." King's American Dispensatory in 1898 named Piper Lowong, P. caninum, P. ribesioides, P. crassipes and "Laurus Cubeba Loureiro," the last being Litsea cubeba under its older name, so the laurel has been the recognized false cubeb for at least 128 years. PROSEA adds that even on Java the cultivars 'rinu badak', 'rinu carulang', 'rinu pedes' and 'rinu tembaga' "are said to be false cubebs," with 'rinu katuncur' and 'rinu cengke' considered true, and calls the identity of the false ones "obscure" and their nomenclature unregulated. Substitution is not a modern fraud layered on a clean tradition; it is the tradition.

The published analyses that look like substitution

Section 2 gave the oils. The 2020 Saudi paper's methods describe a market purchase with no herbarium voucher; the 2024 Moroccan paper gives a voucher (BD-112) and GPS coordinates for a mountain harvest site in a country where Kew does not record the species as native. Both were peer-reviewed and both are now cited as data on Piper cubeba. A buyer reading "studies show" on a label cannot know which is meant.

What third-party testing covers

The author found no current USP-NF monograph for cubeb; the "Cubeba, U.S.P." standard of King's 1898 edition lapsed long ago. NSF and USP verification programs test identity against a reference method only when one exists, so a cubeb product can carry a general GMP seal with no one having confirmed the species. The author found no ConsumerLab review of cubeb. The Arruda HPLC method (2019) is validated to ANVISA and ICH guidelines and Cheng's GC-MS volatile fingerprint (2018) is published with its discriminating markers; neither is required of anyone.

The oldest test still works

PROSEA and the BPC 1911 both record the identity test: cubeb powder on sulfuric acid (80 percent, per PROSEA) gives a crimson color, from the roughly 1 percent cubebic acid. It is a bench test, not a kitchen one, but it has existed since the nineteenth century and a supplier who cannot say whether a lot passed it has not looked.

What a buyer can read off the material

Whole fruit with the stalk attached, 4 to 6 mm, gray-black, hollow inside, with a smell that is camphor-woody and pungent rather than lemon. Lemon means citral, and citral means Litsea. A clove smell means eugenol, and eugenol means the Saudi profile. A certificate for a lot worth trusting states the botanical name with authority (Piper cubeba L.f.), the plant part, the country of origin, GC-MS confirmation that alpha-cubebene and cubebol are present, and a cubebin figure in milligrams per gram by a named HPLC method. If it lists methyleugenol or beta-asarone, it should give a number, and the number should be low.

Special Considerations

The closed chapter

John Crawfurd, a surgeon in the East India Company's Bengal service, wrote from Edinburgh on October 20, 1817, and the Edinburgh Medical and Surgical Journal printed his letter in January 1818 (volume 14, number 53, pages 32 to 34) under the title "Account of the Effects of the Piper Cubeba in Curing Gonorrhoea." He reported that European practitioners on Java had used pounded cubeb for three years against gonorrhea and gleet, a dessert spoonful in water five or six times daily, that the discharge "grows ropy, commonly in 48 hours," and that an Indian servant had first proposed it to "an officer of the Indian army" sailing up the Ganges. He was candid that he had seen only "one or two very satisfactory cases" himself, and that the Javanese used the fruit for children's diseases "but never in gonorrhoea." The journal's editor appended one Edinburgh case that did not go well. On that evidence cubeb entered Western practice, was official in the United States Pharmacopeia that King's 1898 Dispensatory annotated, was described by the BPC of 1911 as an "antiseptic diuretic" used "especially in the advanced stages of gonorrhoea," and remained in use into the twentieth century.

What displaced it is a matter of record. Hook and Kirkcaldy (Clinical Infectious Diseases 2018;67:1294) date "the first reliable medicinal gonorrhea therapy" to the sulfa drugs of the 1930s, note that by 1944 sulfonamide failure rates exceeded 30 percent, and record that gonorrhea "was of sufficient import to have been one of the first infections treated with penicillin" in the 1940s. Penicillin then held for more than 40 years. Current CDC guidance, updated in MMWR on December 18, 2020, is a single intramuscular 500 mg dose of ceftriaxone for patients under 150 kg and 1 g at or above it. The organism is Neisseria gonorrhoeae, it is a notifiable infection, untreated it causes epididymitis, pelvic inflammatory disease and infertility, and no trial of cubeb against it is indexed in PubMed. Products still marketed on the 1818 indication are marketing a treatment that was never shown to work for a disease that now has a cure.

Who the historical dose belongs to

Crawfurd's dessert spoonful of about three drachms, roughly 11.7 g, five or six times a day; the 1898 Dispensatory's 5 grains to 1 drachm of powder three times daily, and its quoted French croup regimen of 15 to 60 grains of oleoresin a day for children; the BPC 1911's 2 to 4 g of powder and 2 to 4 mL of tincture. These are figures from a pre-antibiotic clinic treating a bacterial infection with the only thing on the shelf. They are not a dosing precedent for a modern capsule and they do not appear in Recommended Dosages for that reason.

The two modern gram figures belong here for the same reason. The Jahan 2023 trial gave two capsules of powdered fruit three times daily, stated as 4 g a day, for 42 days, to kidney patients under nephrologist supervision with weekly visits, and 8 of the 15 did not finish. The Unani classical dose Bano and colleagues cite is 3 g of fruit, from a traditional pharmacopeia written for practitioners of that system. Neither is an amount a reader standing in front of a bottle has any basis to take.

The trade that went away

PROSEA records Indonesian cubeb exports of about 270 metric tons in 1925 and an average of 135 metric tons a year until 1940, after which only local trade and some Singapore-to-India traffic remained. The export record ends in 1940, within a few years of the sulfonamides. A smallholder plant yields about 0.5 kg of dried fruit a year, there are no recent production statistics, and the supplement market draws on a supply chain with no quality incentive since before the Second World War.

Research Status & Evidence Quality

Tier 1, human controlled trials

One: Jahan 2023, n = 30 randomized, 17 lost to follow-up, last observation carried forward, open-label, 42 days, early CKD, comparator also improved. No placebo-controlled trial, no pharmacokinetic study, no interaction study.

Tier 2, human observational and historical

Crawfurd 1818 and the Edinburgh military hospital reports it promised, which the author has not located in a later number. A 2024 open-label single-arm Unani study (Qureshi, Drug Metabolism and Personalized Therapy 2024;39:221) gave a 500 mg capsule three times daily for 42 days to patients with Escherichia coli urinary tract infection and reported 83 percent culture conversion. The capsule held 50 percent hydroalcoholic extracts of seven herbs, Kabab Cheeni (Piper cubeba) among them alongside Tribulus terrestris, Phyllanthus niruri and Glycyrrhiza glabra, with no control arm, so it is evidence about a formulation, not about cubeb.

Tier 3, animal

Urolithiasis in rats (Bano 2018), Chagas infection in mice (Esperandim 2010, 2013), carrageenan paw edema in rats (cubebin 53 percent inhibition, per Godoy de Lima), lipofuscin accumulation in rat hippocampus at 400 mg/kg of ethanolic extract, acute toxicity to 2,000 mg/kg extract and 3,000 mg/kg oil. Consistent direction, no human translation.

Tier 4, in vitro

The bulk of the literature: CYP3A4 inactivation (Usia 2005, two papers), antimicrobial MICs (Silva 2007, Alqadeeri 2019), antiandrogen and antiestrogen activity (Yam 2007, 2008), cytotoxicity (Niwa, Rajalekshmi 2016), histamine release, transporter inhibition. Of these only the CYP3A4 work has a mechanism precise enough to act on, and it is the one finding that argues against taking the product.

Research Limitations

• No pharmacokinetics. Drissi's 2022 review says so in those words, and nothing published since changes it. Without a plasma concentration, no in vitro result can be scaled.

• Identity. At least three published chemical profiles of "Piper cubeba" are irreconcilable with each other and with the authenticated Indonesian material. Any review that pools them, as the 2022 review's essential oil table does, produces percentages that sum past 100 and describe no real oil.

• The single trial is open-label with an active comparator that also worked, randomized 15 per arm, and lost 8 of the cubeb patients and 9 of the controls before day 42. Every endpoint is an intention-to-treat figure with the dropouts' last values carried forward, which in a six-week trial means the result leans on people who were in it for less than six weeks.

• Marker confusion. Yatein led the berries in the Indonesian study Drissi cites; cubebin leads in the older literature; Bano's 2018 paper quotes a figure of 0.0024 percent cubebin from an HPLC analysis it cites. Three orders of magnitude of disagreement on the headline compound.

Summary & Key Takeaways

Bottom Line

Cubeb is a Southeast Asian pepper with a 200-year medical history built on one 1818 letter, a pharmacology dominated by lignans that inactivate the enzyme that clears roughly half of all prescription drugs, and a supply chain in which the Chinese Pharmacopoeia names a different plant, three recent peer-reviewed papers report chemistry that does not match the authenticated fruit, and a 1911 codex already complained of substitution. No study has shown it does anything useful in a human that a placebo would not, and the one effect beyond doubt is the one you would not want.

Key Safety Points

• Do not combine with tacrolimus, cyclosporine, simvastatin, lovastatin, midazolam, apixaban, rivaroxaban, fentanyl or any drug a prescriber has told you to keep away from grapefruit. The lignans inactivate CYP3A4 at IC50 0.44 to 1.0 micromolar, ketoconazole's range, and the enzyme does not recover when the dose wears off.

• Not in pregnancy or breastfeeding, and not in children. No data, and the retail label reviewed agrees.

• Methyleugenol (NTP listed 2002) and beta-asarone (behind the 1968 FDA calamus prohibition) have both been found in material sold as cubeb. No capsule states a level.

• The urinary antiseptic claim refers to gonorrhea, was never tested in a trial, and was abandoned in the 1940s. Anyone with the symptom it was sold for needs a swab, not a spice.

• Six weeks is the longest monitored human exposure. Past that there is no data.

Special Note

The strangest fact in the record is in Crawfurd's own letter. The Javanese, who grew the plant and named it kemukus, used it for children's complaints "but never in gonorrhoea." The indication that carried cubeb into every Western pharmacopeia for a century came from an unnamed Indian servant's suggestion to an officer of the Indian army on the Ganges, relayed through a surgeon on Java, written up by a man who admitted he had "no share in the introduction of this remedy" and had seen it work in one patient who shared his lodgings. Everything sold on it since rests on a single anecdote the plant's own people did not share.

Researched and drafted with AI assistance. Every claim verified against primary sources and human-reviewed before publication. Last reviewed: October 15, 2026. Corrections: reply to any issue.

This issue is educational and is not medical advice. If you take prescription medication or have a diagnosed condition, talk to a clinician before adding or stopping anything, including a spice sold in a capsule.