St John's wort is a flowering herb with distinctive translucent dots on its leaves (perforations containing hypericin). The active compounds include hypericin, pseudohypericin, hyperforin, and various flavonoids. It works via multiple mechanisms including serotonin, dopamine, and noradrenaline reuptake inhibition.

Traditional use

Used in ancient Greece and Rome for nerve pain and mental disturbance. Widely used in European folk medicine for depression, anxiety, and wound healing. The traditional harvest date on St John's Day (June 24th) gives the plant its name.

What modern research suggests (Well-supported)

Multiple meta-analyses and Cochrane reviews demonstrate St John's wort is superior to placebo and comparable to standard antidepressants for mild to moderate depression, with significantly fewer side effects. Less effective for severe depression. Evidence also supports use for seasonal affective disorder, anxiety, and premenstrual syndrome.

How people use it

Standard dose: 300mg 3 times daily (standardised to 0.3% hypericin). Takes 4–6 weeks of consistent use for full antidepressant effect—same as prescription antidepressants. Do not combine with other antidepressants. Inform all healthcare providers. Avoid prolonged sun exposure.

Safety + interactions

CRITICAL WARNING: St John's wort is an inducer of CYP3A4 and P-glycoprotein and significantly reduces blood levels of hundreds of medications. This has caused organ transplant rejection (cyclosporine), HIV treatment failure (antiretrovirals), contraceptive failure (oral contraceptives), and bleeding complications (warfarin). Combining with SSRIs/SNRIs risks serotonin syndrome. Photosensitivity can occur. Otherwise well-tolerated.

May interact with: SSRIs, SNRIs, MAOIs, Tricyclic antidepressants, Warfarin, Oral contraceptives, HIV medications, Cyclosporine, Digoxin, Anticonvulsants, Many chemotherapy drugs

Name clarity note

St John's wort has the most significant drug interactions of any herbal medicine. It induces CYP3A4 and P-glycoprotein enzymes, dramatically increasing the metabolism of hundreds of medications. This can lead to therapeutic failure of antidepressants, contraceptives, anticoagulants, and organ rejection medications. ALWAYS inform your doctor and pharmacist if you are taking St John's wort.

Quality notes

Standardisation is essential. Look for products standardised to 0.3% hypericin AND 3–5% hyperforin—both appear important for effect. The German Commission E-approved dose is 900mg/day of 0.3% hypericin extract. Products from Germany and Switzerland (sold as Jarsin, Kira, Remotiv) are among the most studied.

FAQs

Is St John's wort safe to take with my antidepressant?

ABSOLUTELY NOT without medical supervision. Combining St John's wort with SSRIs, SNRIs, or MAOIs risks potentially life-threatening serotonin syndrome. The drug interaction profile of St John's wort is extensive—always consult your doctor and pharmacist before starting it.

Can St John's wort make the pill less effective?

Yes. St John's wort significantly reduces blood levels of oestrogen and progestogen by inducing liver enzymes, which can lead to contraceptive failure and unintended pregnancy. This interaction is well-documented. Use additional contraception if taking both.

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Disclaimer: This content is educational and not medical advice. Always consult a qualified healthcare provider before using any herbs or supplements, especially if you are pregnant, nursing, taking medications, or have a medical condition.

St John's wort

At a glance

What it is