The short answer
St. John's wort can increase the risk of serotonin syndrome when used with amphetamine sulfate. If co-use is necessary, the prescriber may need a lower stimulant starting dose and monitoring, especially when starting or increasing treatment. Do not adjust an existing dose yourself.
What this answer covers
Applies to amphetamine sulfate with St. John's wort products; the risk concerns overlapping effects on serotonin.
- Supplement or preparation
- St. John's wort
- Medication ingredient
- amphetamine sulfate
Evidence and practical considerations
Side effects & toxicity
Exact labeling explicitly lists St. John's wort among serotonergic agents that can increase serotonin-syndrome risk.
- Exact scope
- St. John's wort with amphetamine sulfate
- Medication form and route
- systemic amphetamine sulfate
- Timing or duration
- Risk is relevant during co-use, especially initiation and dose titration.
What remains uncertain
Factors that may matter: higher doses; other serotonergic agents; CYP2D6 inhibitors; history of serotonin toxicity.
Read the supporting source summaries
Source 1: current United States prescribing information
dailymed.nlm.nih.gov · Source check Jul 25, 2026
Population: Patients prescribed oral amphetamine sulfate.
The serotonin-syndrome warning explicitly includes St. John's wort; if co-use is warranted, initiate lower and monitor during initiation or titration.
Label describes agent categories and does not quantify a universal supplement dose, timing interval, or absolute risk.
Research assessment: · Open full citations ↗
Timing & monitoring
Exact labeling names St. John's wort and provides lower-dose and monitoring instructions if co-use is warranted.
- Exact scope
- St. John's wort with amphetamine sulfate
- Medication form and route
- systemic amphetamine sulfate
- Timing or duration
- During co-use and particularly initiation or dose titration.
What remains uncertain
Factors that may matter: other serotonergic agents; higher doses; CYP2D6 inhibition.
Read the supporting source summaries
Source 1: current United States prescribing information
dailymed.nlm.nih.gov · Source check Jul 25, 2026
Population: Patients prescribed oral amphetamine sulfate.
St. John's wort is included in the serotonergic-drug warning; lower initiation and monitoring are advised if co-use is warranted.
Label describes agent categories and does not quantify a universal supplement dose, timing interval, or absolute risk.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Research summary published |
Article revision: 8229106a1dcbfd86
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.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.