Does St John's wort work for depression?
Last updated: June 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy
The real evidence for St John's wort in mild depression — and the serious drug interactions that make it risky.
Key takeaways
- St John's wort has real evidence for mild-to-moderate depression — but not for severe depression.
- It has serious interactions with birth control, blood thinners, antidepressants, HIV and transplant drugs.
- Don't self-treat depression with it — see a doctor, especially if you take any medication.
What St John's wort is
St John's wort is a flowering plant long used for low mood, and one of the few herbal supplements with genuine antidepressant research behind it. That makes it unusual — but it also makes it one of the more dangerous supplements to take casually, because the same activity that may help mood also drives a long list of serious drug interactions. Both halves of that story matter.
The evidence for mild depression
For mild to moderate depression, several studies suggest St John's wort can be more effective than placebo and, in some trials, comparable to standard antidepressants with fewer side effects. The evidence is strongest for milder depression; for severe depression it's not a substitute for proper treatment. So there's a real signal here — but it sits alongside risks that make self-medicating unwise.
The serious interactions
This is the crucial part. St John's wort speeds up liver enzymes that process many medications, which can make them less effective — sometimes dangerously so. It can reduce the effectiveness of hormonal birth control (leading to unintended pregnancy), blood thinners, some heart and HIV medications, immunosuppressants used after transplants, and more. Combined with antidepressants or other serotonergic drugs, it can cause serotonin syndrome, a potentially serious reaction.
Why you can't treat depression alone with it
Beyond interactions, there's the bigger issue: depression deserves proper assessment. Self-treating with a supplement risks missing a condition that needs structured care, delays effective treatment, and — given the interaction list — can be hazardous if you take any other medication. St John's wort is emphatically not a 'safe natural' alternative you can start on your own; it's a substance with real effects and real risks.
Other cautions
St John's wort can also increase sensitivity to sunlight, and stopping it abruptly while on interacting medications can cause its own problems. Quality and the amount of active compounds vary between products. None of this is reason to dismiss it entirely, but all of it is reason to involve a doctor or pharmacist rather than treat it like a casual herbal pick-me-up.
The honest verdict
St John's wort has real evidence for mild depression — and a genuinely serious interaction profile that makes it one of the riskiest supplements to take without medical input. If you're struggling with low mood, the safe and effective path is to see a doctor, who can assess you properly and advise whether St John's wort is appropriate given everything else you take. Do not combine it with other medications on your own.
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Frequently asked questions
Does St John's wort work for depression?
It has evidence for mild-to-moderate depression, sometimes comparable to antidepressants, but not for severe depression.
Is St John's wort safe?
It has serious drug interactions — with birth control, blood thinners, antidepressants and more — so it's risky without medical input.
Can I take St John's wort with my antidepressant?
No — combining them can cause serotonin syndrome. Never combine without a doctor's guidance.
Does it affect birth control?
Yes — it can reduce the effectiveness of hormonal birth control, risking unintended pregnancy.
This article is general information, not medical advice. See our medical disclaimer, and talk to a qualified healthcare professional about your own situation.