Ranked by how strong the human evidence is — best supported first.
Best supportedDigestive comfortNot enough evidence· no source yetThen, in order
The rhizome of a North American woodland plant containing the isoquinoline alkaloids berberine and hydrastine. It is threatened in the wild and much commercial material is cultivated or substituted.
Goldenseal matters less for what it does than for what it does to other drugs: controlled human pharmacokinetic studies show it substantially inhibits CYP3A4 and CYP2D6, raising blood levels of medicines cleared by those enzymes. Meanwhile its traditional uses have almost no clinical trial support, and the popular belief that it masks a urine drug test is false.
Regulation: Listed under CITES Appendix II because of wild-harvest pressure, so international trade is controlled. Adulteration and substitution are common consequences of its price.
The amounts, forms and durations published trials of Goldenseal actually administered.
These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.
Studied for General supplement use
500–3000 mg
Root powder or extract
Trial dosing for goldenseal is not established. The clearest human data come from drug-interaction studies that dosed it specifically to measure enzyme inhibition, which is not a reason to take it.
This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.
Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.
None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.
No timing has been studied. Separating goldenseal from prescription medicines by a few hours does not reliably avoid the enzyme interaction.
Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.
What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.
Evidence is limited for goldenseal and digestive symptoms. Traditional use as a bitter and antimicrobial has not been tested in controlled trials.
Not enough evidence. Not enough human research to say anything useful yet.
There is not enough human research to say goldenseal affects colds or infections, despite its long presence in combination cold products. Its alkaloids are poorly absorbed from the gut.
Not enough evidence. Not enough human research to say anything useful yet.
Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.
Interaction
Interacts withCYP3A4 and CYP2D6 substrates including midazolam, metoprolol, many statins and antidepressants
Controlled studies in volunteers show goldenseal roughly doubles exposure to some drugs cleared by CYP3A4 and CYP2D6 — a category that includes many statins, calcium channel blockers, benzodiazepines, antidepressants and opioid analgesics. This is a demonstrated human interaction, not a theoretical one.
Avoid
Berberine displaces bilirubin from albumin and has been linked to kernicterus risk in newborns. Goldenseal is contraindicated in pregnancy and breastfeeding and should never be given to infants.
Worth knowing
Because wild goldenseal is expensive and protected, retail products have been found substituted with cheaper berberine-containing plants or containing no goldenseal at all.
Worth knowing
Large amounts have been associated with mouth and stomach irritation, nausea and, at extremes, effects on heart rhythm and blood pressure.
Worth knowing
The belief that goldenseal conceals drugs in urine originates in a 19th-century novel. Testing has found no such effect.