St John’s Wort should not be taken alongside an antidepressant. Both raise serotonin activity, and together they can cause serotonin syndrome, which ranges from unpleasant to life-threatening.
This combination happens more often than it should, usually for an understandable reason: someone is prescribed an antidepressant, wants to add something natural alongside it, and does not think of a herbal product as a medicine that could clash. It is a medicine, and it does.
Common side effects reported with this supplement or ingredient
Taken on its own, St John’s Wort causes mild effects: stomach upset, tiredness, restlessness, dry mouth, headache, and increased sensitivity to sunlight. See St John’s Wort side effects.
Possible interactions with medicines, chronic conditions or pregnancy
Serotonin syndrome is the main concern. Symptoms usually come on within hours of a dose and include agitation or confusion, fever and sweating, a racing heartbeat, muscle twitching or stiffness, shivering, and diarrhoea. Mild cases can look like anxiety with a stomach upset, which is part of why it gets missed.
The risk applies with SSRIs, SNRIs, tricyclics and other antidepressants, and it increases further alongside tramadol or migraine triptans. See serotonin syndrome symptoms.
Switching between them also needs care. A gap is usually needed when moving from one to the other, in both directions, rather than stopping one and starting the other the next day. How long depends on which antidepressant, so this is a question for your prescriber rather than something to plan yourself.
St John’s Wort also reduces the effectiveness of many other medicines, so if you take anything else, that matters too. See the full interactions guide.
Who should speak to a healthcare professional before using it?
Anyone currently taking an antidepressant, anyone who has recently stopped one, and anyone considering St John’s Wort instead of prescribed treatment.
That last group deserves a direct answer. Wanting to try something other than a prescription is a reasonable position, and worth discussing rather than acting on alone. Depression that is being treated is not a good moment to change approach without telling anyone, and stopping an antidepressant abruptly to switch causes its own problems. See stopping antidepressants.
Dose, product-quality and stacking risks
Herbal preparations vary widely in active content, so two products at the same stated dose can behave differently and the size of an interaction is not predictable from the label. St John’s Wort also appears inside combination mood, sleep and stress formulas without always being prominent on the front of the pack, so read the full ingredient list before assuming a product does not contain it.
When to stop and get medical advice
Get emergency help for agitation or confusion together with fever, sweating, a racing heart, muscle twitching and diarrhoea.
Contact your prescriber promptly if you have been taking both without telling them. Do not stop the antidepressant. Stop the St John’s Wort and ask, since the antidepressant may need monitoring as levels shift.
Related supplement safety guides
- Supplement and medicine interactions
- St John’s Wort interactions
- Supplement side effects
- When to see a doctor about a supplement
- Report a supplement side effect
See also supplements with antidepressants.
Medical Disclaimer: This content is for informational and educational purposes only and does not constitute medical diagnosis, prescription, or professional advice. Always read the patient information leaflet and consult a qualified doctor or pharmacist regarding any medicine or health concern.