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Goldenseal (Hydrastis canadensis; berberine/hydrastine)
A traditional immune/antimicrobial herb whose most important real-world property is its drug-interaction potential (CYP3A4/2D6 inhibition); efficacy evidence is essentially absent.
What the evidence says
Goldenseal doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from medium-quality randomised trials published 2005–2025.
Based on 14 studies · 5 RCTs
Confidence
Moderate confidenceBy outcome
Controlled human probe-drug studies confirm real CYP3A4/2D6 inhibition (a drug-interaction concern), but there is essentially no human efficacy evidence for its traditional immune or antimicrobial uses, keeping the score low.
No trials currently enrolling · 7 completed on ClinicalTrials.gov
2 of the completed trials have posted results
Registered trials show research momentum for Goldenseal, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Oct 2026
Goldenseal (Hydrastis canadensis) is a traditional North American herb containing berberine and hydrastine, marketed for immune support, colds, and digestive/mucosal health. There is essentially no human efficacy evidence for any of those uses.
What goldenseal IS documented for is inhibiting the drug-metabolizing enzyme CYP3A4 (and, to a lesser degree, CYP2D6) — controlled human probe-drug studies confirm a real effect, though a systematic review classifies it as a weak inhibitor at commonly recommended doses, and several studies found NO meaningful interaction with P-glycoprotein/digoxin, metformin, or other transporter substrates.
This card exists mainly so the CYP-interaction caution is visible: treat goldenseal as a use-with-caution herb, not a casual immune supplement.
Inhibits CYP3A4 (and, to a lesser degree, CYP2D6) in human studies — a real but modest/weak effect at typical doses that can still slow the metabolism of some drugs. Does not meaningfully affect P-glycoprotein/transporter substrates such as digoxin or metformin.
Contains berberine, which has antimicrobial activity in the lab.
Traditionally used as an astringent on mucous membranes.
Avoid unless cleared by a pharmacist/clinician — high CYP drug-interaction risk.
Avoid — berberine can cross the placenta and displace bilirubin (kernicterus risk).
Avoid.
Goldenseal strongly inhibits CYP3A4 — can raise drug levels to toxic ranges.
Inhibits CYP2D6 — altered drug levels and effects.
Modestly reduces metformin exposure in human studies; no clinically meaningful interaction overall (and digoxin pharmacokinetics unaffected).
CYP inhibition can dangerously alter HIV drug levels.
Tip: Take with food; short courses
Tip: Avoid if hypertensive
Tip: Reduce dose
Goldenseal has an evidence score of 3.5/10 — emerging evidence based on 14 indexed studies. A traditional immune/antimicrobial herb whose most important real-world property is its drug-interaction potential (CYP3A4/2D6 inhibition); efficacy evidence is essentially absent. Representative study: PMID 22855269.
Dosing for Goldenseal: Traditional: 0.5-1g root (or ~250-500mg extract) up to 3x daily, short-term — but weigh against significant drug-interaction risk (a traditional dose, the one cited trial that states a dose gave 3,210 mg a day). Individual needs vary — start at the lower end of the range and adjust based on how you respond.
The best time to take Goldenseal is with meals. Taking it with food is preferred. Taken with food short-term; most importantly, separate from and avoid with medications affected by CYP3A4/2D6.
Goldenseal should be used with caution — talk to a healthcare provider before taking it. Reported side effects include raised blood pressure, GI upset, mucosal irritation. How often they occur is not established for all of them. Use caution if any of these apply to you: Concurrent use of any CYP3A4 or CYP2D6-metabolized medication; Pregnancy and breastfeeding (berberine crosses placenta; risk of kernicterus in newborns); Hypertension.
Andrographis
Likely helpsStudied for comfort and symptom duration during upper-respiratory infections when taken at onset — also supports liver health.
Chlorella
Too few graded studiesFreshwater algae with the highest chlorophyll content of any plant — binds heavy metals and supports detoxification pathways.
Pelargonium Sidoides
Too few graded studiesA standardized root extract (EPs 7630) of the South African geranium, best evidenced for shortening symptom duration and severity in acute bronchitis and other upper-respiratory infections. The Cochrane review found the liquid preparation effective for acute bronchitis but rated overall evidence quality as low to very low.
Cranberry Extract
Mixed evidenceWell-researched extract that prevents UTI-causing bacteria from adhering to the urinary tract — best for prevention, not treatment.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 14 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.