St. John's Wort
Useful mainly for adults with mild-to-moderate depression not on interacting medications.
Quick decision guide
May help most
adults with mild-to-moderate depression not on interacting medications
Common dosing range
300 mg three times daily (900 mg/day) standardized extract
When to expect effects
2-6 weeks
Watch out for
Many serious drug interactions via CYP3A4/P-gp induction.
What is it
St. John's wort (Hypericum perforatum) is a flowering plant native to Europe whose aerial parts (flowers and leaves) have been used medicinally for centuries. It is one of the most studied herbal supplements, primarily for mild to moderate depression. The plant gets its name from blooming around the feast day of St. John the Baptist (June 24).
Is it worth it for you?
Use this as a quick fit check, not a diagnosis.
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Evidence at a glance
| Goal | Effect | Best fit | Time |
|---|---|---|---|
mild to moderate depression Strong Evidence | Comparable to standard antidepressants in mild-to-moderate cases | adults with mild-to-moderate depression and no interacting medications | 2-6 weeks |
seasonal affective disorder Limited Evidence | Modest, uncertain | people with seasonal (winter) depressive symptoms | Weeks |
menopausal mood symptoms Limited Evidence | Modest | menopausal women with mood-related symptoms | Weeks |
mild to moderate depression
- Effect
- Comparable to standard antidepressants in mild-to-moderate cases
- Best fit
- adults with mild-to-moderate depression and no interacting medications
- Time
- 2-6 weeks
seasonal affective disorder
- Effect
- Modest, uncertain
- Best fit
- people with seasonal (winter) depressive symptoms
- Time
- Weeks
menopausal mood symptoms
- Effect
- Modest
- Best fit
- menopausal women with mood-related symptoms
- Time
- Weeks
Evidence for 3 uses
AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.
mild to moderate depression
Supplement benefitCochrane meta-analyses of numerous randomized trials find standardized St. John's wort extracts superior to placebo and broadly comparable to standard antidepressants for mild-to-moderate depression, with fewer side effects. Hyperforin inhibits monoamine reuptake, consistent with the observed effect. The main caveat is heterogeneity in extracts and the herb's extensive drug interactions.
Bottom line: Standardized St. John's wort works about as well as standard antidepressants for mild-to-moderate depression.
seasonal affective disorder
Supplement benefitSmall studies, sometimes combined with light therapy, suggest St. John's wort may help seasonal affective disorder symptoms. The evidence is limited and less robust than for general mild-to-moderate depression. Benefit is plausible but not well established for this indication specifically.
Bottom line: May help seasonal affective disorder, but evidence is limited.
menopausal mood symptoms
Supplement benefitSome trials, often using St. John's wort alone or combined with black cohosh, report improvement in mood-related menopausal symptoms. Evidence is limited and effect size modest. It targets mood symptoms rather than vasomotor symptoms specifically.
Bottom line: May modestly improve mood-related menopausal symptoms, on limited evidence.
How it works
How to take it
What to track
4 commercial forms
Compare the main delivery options and what they’re best suited for.
Standardized extract (0.3% hypericin)
Standardized to hypericin content. Used in many European and North American depression trials.
Most common clinical-trial standardization
Standardized extract (3-5% hyperforin)
Hyperforin is now considered the primary antidepressant compound. Some newer products use this standardization.
Standardized to current understanding of active compound
Dried herb (whole flower/leaf)
Used in teas and traditional preparations. Inconsistent compound content.
Variable potency
Liquid extract / tincture
Concentrated form, used in traditional and herbalist applications.
Alcohol-based extraction
Safety
Know the common side effects, key cautions, and who should avoid it.
Common side effects
Serious risks
serotonin syndrome when combined with serotonergic drugs
mania/hypomania in undiagnosed bipolar disorder
loss of efficacy of many medications via enzyme induction
Who should avoid it
- pregnant or breastfeeding women
- people on interacting prescription medications
- people with bipolar disorder or schizophrenia
- those approaching surgery (stop 1-2 weeks prior)
Pregnancy & breastfeeding
Avoid in pregnancy and breastfeeding due to insufficient safety data.
Interactions
induces metabolism and can cause contraceptive failure/unintended pregnancy
risk of serotonin syndrome
reduces anticoagulant effect via enzyme induction
reduced drug levels risking transplant rejection
reduced drug effectiveness via CYP3A4/P-gp induction
reduced drug levels via enzyme/transporter induction
Documented interactions
Evidence-graded pair pages with sources, dosing notes, and timing guidance — a complement to the narrative section above.
Warnings (31)
+ sertraline
criticalSertraline is an SSRI that blocks serotonin reuptake, and St. John's wort independently raises central serotonin through constituents such as hyperforin and hypericin. Combining them can trigger serotonin syndrome, a potentially life-threatening reaction marked by altered mental status, autonomic instability, and neuromuscular hyperactivity. St. John's wort also induces CYP3A4 and CYP2C19, which can lower sertraline levels and undermine treatment.
+ cyclosporine
criticalSt. John's wort is a potent inducer of CYP3A4 and P-glycoprotein, the enzyme and transporter that clear cyclosporine. Taking the two together markedly lowers cyclosporine blood levels, which can render the drug subtherapeutic. This has caused documented acute organ rejection in transplant recipients, making the combination a contraindication.
+ oral contraceptives
criticalSt. John's Wort induces CYP3A4 and P-glycoprotein, increasing the clearance of contraceptive hormones and reducing the effectiveness of hormonal contraceptives.
+ maoi
criticalSt. John's Wort raises brain serotonin, norepinephrine, and dopamine through reuptake inhibition and shows weak monoamine oxidase inhibition. Layered on a prescription MAOI, which blocks the breakdown of those same monoamines, the combination can push monoamine signaling to dangerous levels and is contraindicated because of the risk of serotonin syndrome and hypertensive crisis.
Choosing a product
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Frequently asked questions
Is St. John's wort as good as prescription antidepressants?⌄
For mild to moderate depression, meta-analyses show similar efficacy with fewer side effects. For severe depression, prescription medications under medical supervision are recommended. St. John's wort is not appropriate as DIY treatment for serious depression.
Can I take St. John's wort with my birth control pills?⌄
No. St. John's wort significantly reduces the effectiveness of oral contraceptives, potentially leading to unintended pregnancy. Use additional contraception or choose a different supplement.
Does St. John's wort interact with other medications?⌄
Yes, extensively. It induces liver enzymes that metabolize many medications, reducing effectiveness of drugs including warfarin, immunosuppressants, antiretrovirals, certain chemotherapy drugs, and many others. Always check with a pharmacist or physician before combining.
How long until St. John's wort works?⌄
Effects on mood typically emerge over 2 to 6 weeks of consistent daily use, similar to prescription antidepressants.
Can St. John's wort cause sunburn?⌄
Yes. Hypericin causes photosensitivity. Use sunscreen and avoid prolonged sun exposure, especially at higher doses and in fair-skinned individuals.
References by claim
mild to moderate depression
seasonal affective disorder
Track St. John's Wort with Pilora
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Coming to App StoreDisclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.