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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
Most Goldenseal studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality randomised trials published 2005–2025.
Based on 9 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momentum for Goldenseal, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed.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 Sep 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 8 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.
The commonly studied dose of Goldenseal is Traditional: 0.5-1g root (or ~250-500mg extract) up to 3x daily, short-term — but weigh against significant drug-interaction risk. 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 are uncommon and include GI upset, raised blood pressure, mucosal irritation. 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.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 9 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.