The short answer
Goldenseal may increase dextromethorphan exposure by slowing metabolism. Human enzyme studies support the concern, but available combination case reports did not measure drug levels or prove increased intestinal absorption.
What this answer covers
Hydrastis canadensis root extracts; not isolated berberine or every commercial preparation.
- Supplement or preparation
- Hydrastis canadensis
- Medication ingredient
- dextromethorphan
Metabolism is the main concern
Goldenseal inhibited CYP2D6 in a debrisoquine probe study and CYP3A in a midazolam study. These findings support a possible change in dextromethorphan handling, without providing a measured increase for this exact pair.
The direct reports have important limits
Two psychiatric case reports describe improvement after adding goldenseal to regimens containing dextromethorphan and other medicines. Neither measured dextromethorphan levels. Reported tolerability in these individuals does not establish safety or cough benefit.
Absorption and exposure are different
Slower breakdown can raise drug exposure without increasing the amount absorbed through the intestine. Product composition, other medicines and individual metabolism can change the outcome; no exact percentage or automatic dose adjustment is established.
Do not use the case reports as a dosing plan
Ask a pharmacist or prescriber before co-use or a change in goldenseal use. Follow the exact cough formulation’s directions and do not add goldenseal to prolong its effects. A short dosing gap is not proven protection.
Evidence and practical considerations
Absorption & effectiveness
Conditional increased-exposure concern from human goldenseal enzyme inhibition and exact-pair clinical observations, without measured drug levels or proof of increased intestinal absorption; psychiatric cases do not establish cough efficacy or safety.
- Exact scope
- Hydrastis canadensis root extracts; not isolated berberine or every commercial preparation. with Dextromethorphan3289 IN; oral cough hydrobromide/polistirex formulations, not codeine or other pain opioids; psychiatric combinations explicitly limited.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- No unmeasured pair incidence, blanket class transfer or arbitrary spacing interval.
Factors that may matter: Preparation; Dose; Other medicines; Organ function.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed dextromethorphan
Cough suppressant with age-specific directions, overdose precautions and prohibition during prescription MAOI use or within2weeks after stopping that drug.
How this applies: Exact dextromethorphan RxCUI 3289 IN, with stated salt/formulation/route bridge.
Not a pain opioid label, not a sedating antihistamine combination, and MAOI interval cannot be assigned to every herb.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed dextromethorphan
Different age-specific schedule and release duration from caplets; MAOI prohibition and overdose precautions.
How this applies: Exact dextromethorphan RxCUI 3289 IN, with stated salt/formulation/route bridge.
Not interchangeable dosing with immediate-release products or psychiatric combinations containing a CYP2D6 inhibitor.
Source 3: national medication patient information
medlineplus.gov · Source check Sep 10, 2026
Population: People using dextromethorphan cough medicines
Possible dizziness and drowsiness; disclose supplements and other medicines; overdose can cause serious neurologic and breathing problems.
How this applies: Exact medication effects and review advice.
No exact supplement interaction incidence; overdose outcomes are not routine therapeutic-dose event rates.
Source 4: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 16 healthy volunteers in the relevant study.
CYP2D6 activity decreased after goldenseal; other tested extracts, including kava and St John’s wort, did not significantly inhibit this probe measure.
How this applies: Original source interpreted for dextromethorphan only within the stated preparation and endpoint limits.
Human debrisoquine CYP2D6 or midazolam CYP3A probe study, not measured dextromethorphan exposure; no intestinal-absorption percentage established.
Source 5: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 16 healthy volunteers.
Goldenseal increased midazolam exposure; kava did not significantly alter its disposition.
How this applies: Original source interpreted for dextromethorphan only within the stated preparation and endpoint limits.
Human debrisoquine CYP2D6 or midazolam CYP3A probe study, not measured dextromethorphan exposure; no intestinal-absorption percentage established.
Source 6: original case report
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: One32-year-old man with bipolar depression/OCD symptoms.
Transient mood improvement with stopping/restarting association; no reported hypomanic switch or adverse event during brief exposure.
How this applies: No plasma dextromethorphan levels or CYP2D6 markers; polypharmacy, spontaneous fluctuation and expectancy confound benefit. Not cough treatment.
No plasma dextromethorphan levels or CYP2D6 markers; polypharmacy, spontaneous fluctuation and expectancy confound benefit. Not cough treatment.
Source 7: original case report
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: One16-year-old with OCD.
Symptoms improved and no goldenseal adverse events were reported during brief follow-up; residual fatigue persisted.
How this applies: No measured dextromethorphan concentration or laboratory safety monitoring; polypharmacy and clinical assessment cannot prove metabolic magnitude or safety.
No measured dextromethorphan concentration or laboratory safety monitoring; polypharmacy and clinical assessment cannot prove metabolic magnitude or safety.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Prepared exact dextromethorphan article with formulation-specific evidence and uncertainty. | |
| Research summary published |
Article revision: f932814d522c8ee2
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
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Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.