Piper methysticum · PhytoNexus

01 Identity and provenance

Accepted binomial: Piper methysticum
Common names: Kava
Family (APG IV): Piperaceae
Part used: Rhizome
Verification tier: Tier 2 · Verified Clinical columns reviewed and a source is on record.
Reviewer note (2026 audit): Reference not supplied - claim unverified against primary literature.

02 Constituent chemistry

Chemical class	Marker compound	Synthetic analogue in use
Kavalactones, Chalcones, Flavokavains, Alkaloids	Kavain, Dihydrokavain, Methysticin, Dihydromethysticin, Yangonin, Desmethoxyyangonin Rhizome	Diazepam, Lorazepam, Clonazepam, Buspirone, Zolpidem (GABAergic anxiolytic similarity); Baclofen (CNS depressant properties)

The analogue column is what makes the interaction reasoning tractable: where a constituent has a marketed structural counterpart, the counterpart's interaction profile is the starting hypothesis for the plant.

Looking up structures and physicochemical properties from PubChem…

03 Stated application

Reported activity: Anxiety, stress, insomnia, muscle relaxation, mild depression, menopausal anxiety
Marketed in: Kava capsules, tablets, tinctures, herbal teas, liquid extracts
Reported adverse effects: Drowsiness, dizziness, impaired coordination, hepatotoxicity (rare but serious), gastrointestinal upset, skin changes with prolonged use

04 Interaction matrix

Source column, verbatim: Benzodiazepines, barbiturates, alcohol, opioids, antidepressants, antipsychotics, levodopa, hepatotoxic drugs, anesthetics
Normalised onto 8 canonical drug classes below.

Curated from the reviewed source

Drug class	Severity	Mechanism type	Provenance	Expected effect
Alcohol CNS	4Contraindicated	PD-additive + organ toxicity	curated B	Excess sedation, impaired judgement, higher risk of botanical hepatotoxic…	why ▾
Chemistry of this pair. Kavalactones enhance GABA-A binding, block voltage-gated sodium channels and inhibit CYP1A2, 2C9, 2C19, 2D6 and 3A4. Class mechanism. Additive CNS depression plus shared hepatic injury pathways; alcohol also increases the extraction and absorption of lipophilic botanical constituents from tinctures. Expected Excess sedation, impaired judgement, higher risk of botanical hepatotoxicity. Management Advise abstinence with sedative or hepatotoxic botanicals; note the ethanol content of tinctures in recovering patients. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “alcohol” Find evidence for this pair Map this mechanism
Hepatotoxic drugs Organ toxicity	4Contraindicated	Organ-toxicity additive	curated B	Transaminase elevation, cholestasis, sinusoidal obstruction syndrome, acu…	why ▾
Chemistry of this pair. Kavalactones enhance GABA-A binding, block voltage-gated sodium channels and inhibit CYP1A2, 2C9, 2C19, 2D6 and 3A4. Class mechanism. Pyrrolizidine alkaloids, high-dose anthraquinones, kava constituents and germander-type diterpenes cause hepatocellular or sinusoidal injury that adds to the risk from paracetamol, isoniazid, methotrexate, azoles and statins. Expected Transaminase elevation, cholestasis, sinusoidal obstruction syndrome, acute liver failure. Management Baseline and 4-weekly ALT and bilirubin. Stop the botanical at any transaminase rise above three times the upper reference limit. Onset unspecified Evidence B - reviewed clinical column, source pending Matched on “hepatotoxic drugs” Find evidence for this pair Map this mechanism
Sedatives, hypnotics and benzodiazepines CNS	4Contraindicated	PD-additive	curated B	Excess sedation, psychomotor and driving impairment, falls, respiratory d…	why ▾
Chemistry of this pair. Kavalactones enhance GABA-A binding, block voltage-gated sodium channels and inhibit CYP1A2, 2C9, 2C19, 2D6 and 3A4. Class mechanism. Valepotriate, kavalactone, apigenin, sesquiterpene and alkaloid constituents act at GABA-A, adenosine and histamine sites, summating with prescribed CNS depression. Some also inhibit CYP3A4 and raise benzodiazepine exposure. Expected Excess sedation, psychomotor and driving impairment, falls, respiratory depression when combined with opioids. Management Warn against driving and machine operation. Avoid triple combinations with opioids. Reduce hypnotic dose in older adults. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “benzodiazepines” Find evidence for this pair Map this mechanism
Antidepressants (SSRI, SNRI, TCA) CNS	3Major	PD-additive serotonergic + PK-CYP2D6	curated B	Serotonin syndrome (agitation, clonus, hyperthermia, autonomic instabilit…	why ▾
Class mechanism. Hypericin- and hyperforin-type constituents inhibit monoamine reuptake and induce CYP3A4/2C19 and P-glycoprotein; others inhibit CYP2D6, raising tricyclic and SSRI concentrations. Expected Serotonin syndrome (agitation, clonus, hyperthermia, autonomic instability) or loss of antidepressant effect on withdrawal of an inducer. Management Screen for serotonergic burden before adding. Taper rather than stop abruptly. Consider therapeutic drug monitoring for tricyclics. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “antidepressants” Find evidence for this pair Map this mechanism
Antipsychotics CNS	3Major	PD-additive + PK-CYP	curated B	Extrapyramidal symptoms, QT prolongation, excess sedation, or loss of ant…	why ▾
Class mechanism. Additive dopaminergic blockade, QT prolongation and sedation, plus CYP1A2, 2D6 and 3A4 modulation of clozapine, risperidone and quetiapine exposure. Expected Extrapyramidal symptoms, QT prolongation, excess sedation, or loss of antipsychotic control with inducers. Management ECG if other QT-prolonging agents are present. Consider clozapine level monitoring where inducers are stopped or started. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “antipsychotics” Find evidence for this pair Map this mechanism
General and local anaesthetics (perioperative) Perioperative	3Major	PD-additive + PK-CYP	curated B	Prolonged emergence, intraoperative haemodynamic instability, excess surg…	why ▾
Class mechanism. Botanical CNS depressants prolong anaesthetic recovery, antiplatelet and coumarin constituents raise surgical bleeding, and sympathomimetics destabilise intraoperative haemodynamics. CYP modulation changes opioid and muscle-relaxant handling. Expected Prolonged emergence, intraoperative haemodynamic instability, excess surgical bleeding, delayed neuraxial haematoma. Management Ask about all botanicals at pre-anaesthetic assessment and stop them 1-2 weeks before surgery unless there is a reason not to. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “anesthetics” Find evidence for this pair Map this mechanism
Levodopa and antiparkinsonian drugs CNS	3Major	PK-absorption + PD-antagonistic	curated B	Dyskinesia and hypotension from additive L-DOPA; unpredictable off period…	why ▾
Class mechanism. Mucuna species contain L-DOPA itself, so co-administration is unblinded dose escalation. High-protein and high-pyridoxine botanical products reduce levodopa absorption and central availability, and dopamine-antagonist constituents oppose its effect. Expected Dyskinesia and hypotension from additive L-DOPA; unpredictable off periods and motor fluctuation from reduced absorption. Management Count botanical L-DOPA in the total daily dose. Keep dosing separate from protein-rich products by at least 30 minutes. Onset unspecified Evidence B - reviewed clinical column, source pending Matched on “levodopa” Find evidence for this pair Map this mechanism
Opioid analgesics CNS	3Major	PD-additive + PK-CYP2D6/3A4	curated B	Respiratory depression, over-sedation, constipation, ileus; unpredictable…	why ▾
Class mechanism. Botanical mu-agonists and CNS depressants add to opioid respiratory and sedative effect; CYP2D6 and CYP3A4 modulation alters the conversion of codeine and tramadol to active metabolites. Expected Respiratory depression, over-sedation, constipation, ileus; unpredictable analgesia in CYP2D6 poor or ultrarapid metabolisers. Management Avoid concurrent botanical sedatives. Counsel on overdose signs and ensure naloxone availability where risk is high. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “opioids” Find evidence for this pair Map this mechanism

Predicted from constituent chemistry

These edges are not clinical findings. Each one is a rule inference: a constituent class in this plant is known to act on a target that the drug class also acts on. They are shown because a blank cell reads as “safe”, and for a Tier 1 entry a blank cell only means “not yet looked at”. Treat them as a literature-search agenda, not as a warning.

Drug class	Severity	Mechanism type	Provenance	Expected effect
Narrow-therapeutic-index CYP3A4 substrates Pharmacokinetic	4Contraindicated	PK-CYP3A4	predicted D	Toxic accumulation or subtherapeutic failure of the co-prescribed drug, s…	why ▾
Chemistry of this pair. Kavalactones enhance GABA-A binding, block voltage-gated sodium channels and inhibit CYP1A2, 2C9, 2C19, 2D6 and 3A4. Class mechanism. Furanocoumarins, bergamottin, piperine, glabridin and berberine inhibit CYP3A4; hyperforin, andrographolide and several diterpenes induce it through PXR. Because CYP3A4 handles roughly half of marketed drugs, the affected list is broad and the direction is product-specific. Expected Toxic accumulation or subtherapeutic failure of the co-prescribed drug, sometimes fatal for antiarrhythmics, immunosuppressants and oncology agents. Management Screen the full regimen for 3A4 substrates. Where the substrate has a narrow index, avoid rather than monitor. Onset unspecified Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism
Antacids, PPIs and H2 blockers Gastrointestinal	2Moderate	PK-absorption	predicted D	Reduced or erratic absorption of alkaloids; heartburn and reflux from pre…	why ▾
Chemistry of this pair. Alkaloidal bases have pH-dependent absorption and commonly interact with hepatic CYP isoenzymes and efflux transporters. Class mechanism. Gastric pH elevation alters the dissolution and ionisation of alkaloidal and enteric-coated botanical products; menthol- and peppermint-oil products lose their enteric protection at high pH and can be released prematurely. Expected Reduced or erratic absorption of alkaloids; heartburn and reflux from premature release of volatile-oil preparations. Management Separate administration by 2 hours. Avoid non-enteric peppermint oil in reflux disease. Onset unspecified Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism

05 Hazard register

The audit recorded no hazard beyond the interaction profile. The controlled-vocabulary field reads not assessed, which means the assessment has not been done rather than that it came back clear.

06 Confusable material

These entries could be mistaken for this one in trade, in the herbarium, or in a prescription. Powdered material is often indistinguishable, so the check is macroscopic, microscopic and chromatographic rather than nominal.

Piper longum Long Pepper	Piperaceae	Same genus (Piper)
Piper nigrum Black Pepper	Piperaceae	Same genus (Piper)

07 Mechanism map

Chemistry sorts to the left, pharmacology to the right. Dashed edges are predicted. Drag nodes, scroll to zoom, export at 3× for a figure.

species

chemical class

marker compound

drug class

expected effect

hazard

08 Open literature

Abstract-scoped query built from this binomial, its common names and its marker compounds, run live against Europe PMC, PubMed and OpenAlex, then ranked locally against an evidence hierarchy.

Checking openFDA spontaneous reports…

09 Isomechanistic neighbours

Species whose interaction profile overlaps this one, ranked by shared severity weight rather than by count — a shared contraindication counts for more than a shared minor signal. Practical use: these are the plants you should not stack with this one, because the mechanisms summate.

Species	Family	Shared classes	Jaccard
Mitragyna speciosa Kratom	Rubiaceae	6	0.46
Nardostachys jatamansi Jatamansi	Caprifoliaceae	5	0.36
Valeriana jatamansi Tagar	Caprifoliaceae	5	0.38
Strychnos nux-vomica Nux Vomica	Loganiaceae	4	0.27
Mucuna pruriens Mucuna	Fabaceae	4	0.36
Peganum harmala Syrian Rue	Nitrariaceae	4	0.29

10 References and notes

No citation is on record for this entry. That is itself the finding: the audit flagged it, and it is why the entry does not carry an A evidence grade.

Curator notes

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