Awaiting clinical review. This entry is sourced but has not yet been signed off by a pharmacist or clinician.

Hypericum perforatum (aerial parts)

St John's wort

St John's wort extracts probably help some people with mild to moderate depression: a Cochrane review found them better than placebo and about as effective as standard antidepressants, though the results were uneven and one large US trial in more severe depression found no benefit. It appears safe on its own for up to 12 weeks, but it speeds up the breakdown of many prescription medicines and can add to the effect of antidepressants, so check with a doctor or pharmacist before taking it alongside any medicine. The evidence cannot tell you whether it works for severe depression or beyond about 12 weeks.

Written by

Healthy and Herbal editorial team

Updated

29 September 2026

At a glance

Last reviewed 29 September 2026

Evidence

Moderate

Best for

Mild to moderate depression

Typical form & use

Dry extract, 300–600 mg 1–3 times daily

Onset

4+ weeks

Safety

Interacts with many medicines, incl. the pill and SSRIs. 10 known interactions, most serious with blood thinners.

Check with your medications →

What it's used for

Evidence is rated per use. The same ingredient can be strong for one thing and traditional for another.

Use	Evidence	What the research shows
Mild to moderate depression	Moderate	The Cochrane review (29 trials, 5,489 people, most with major depression) found extracts beat placebo: response rate ratio 1.28 (95% CI 1.10 to 1.49) in nine larger trials and 1.87 (1.22 to 2.87) in nine smaller ones, with marked heterogeneity and stronger results from German-speaking countries. Against standard antidepressants the response ratio was 1.00 for SSRIs (12 trials) and 1.02 for older antidepressants (5 trials), with fewer dropouts from side effects. A 2017 meta-analysis of 27 trials against SSRIs (4 to 12 weeks) agreed. We rate it 3 rather than 4 because of the heterogeneity and country effect, short trials, and manufacturer links among some reviewers.^1,2,4,5
Moderately severe major depression	Limited	In a US trial of 340 adults with major depression (HAM-D of 20 or more), St John's wort at 900 to 1,500 mg daily did not beat placebo at 8 weeks (full response 23.9% vs 31.9%), and neither did sertraline, so the trial may have been insensitive. NCCIH says it is uncertain whether the benefit holds for severe depression or beyond 12 weeks.^3,4
Menopausal hot flushes	Limited	NCCIH reports that a small number of studies suggest it may help hot flashes, but the evidence is not clear enough to draw conclusions. We did not read those trials ourselves, so this rests on NCCIH's summary.⁴
Minor skin inflammation and wounds (topical)	Traditional	The EU regulator recognises oil-based and other preparations applied to the skin for minor inflammation such as sunburn and to aid healing of minor wounds, on the basis of long-standing use only. NCCIH says research on topical use for wounds is too limited to show benefit. Topical use can still cause photosensitive skin reactions.^4,5

How much

Ranges below are what studies used and what supplements commonly contain. They are not a recommendation for you. Start at the low end.

Studied range (depression)

300–600 mg dry extract per dose^5,3

The EU monograph's well-established-use dose for the methanol and ethanol dry extracts, taken 1 to 3 times daily (600 to 1,800 mg a day). Other extracts are dosed differently: 900 mg once daily, or 600 mg once daily. The US trial used 900 to 1,500 mg daily.

Time to effect

Up to 4 weeks⁵

The EU monograph says the onset of effect can be expected within 4 weeks, and to consult a doctor if symptoms persist during use.

Duration studied

Up to 12 weeks^4,2

NCCIH says it appears safe in adults taking no medicines for up to 12 weeks, with some studies supporting a year or more. The trials in the 2017 meta-analysis lasted 4 to 12 weeks.

Overdose signal

About 4.5 g a day for 2 weeks⁵

The EU monograph records seizures and confusion after up to 4.5 g of dry extract a day for 2 weeks plus 15 g just before hospitalisation, and advises protection from sunlight for 1 to 2 weeks after a massive overdose.

Timing · No source we read gave a time of day. The EU monograph gives single doses taken once to three times daily depending on the extract.With food? · No source we read gave food guidance. Stomach upset (nausea, abdominal pain, diarrhoea) is listed as a possible effect.How long to trial · The EU monograph says the effect can be expected within 4 weeks and to see a doctor if symptoms persist. Depression can be serious, so do not treat it alone with a supplement if it is more than mild or is getting worse.

How people take it

Tablet or capsule (dry extract)300–600 mg per dose, 1–3 times dailyThe form with the clinical trials and the EU well-established use. Extracts differ in hyperforin content, and the strength of the drug interactions tracks hyperforin, so products are not interchangeable.

Tincture or liquid extractVaries by strength; follow the labelListed under traditional use in the EU monograph only, with single doses from about 1 to 20 ml depending on the preparation. Not the form tested in most depression trials.

Herbal tea1.5–2 g herb in 150 ml boiling water, 2–3 times dailyTraditional use only, for temporary mental exhaustion. No trial evidence for depression.

Oil or liquid, applied to skinUndiluted preparation applied to the skinTraditional use for minor skin inflammation and wounds. Avoid intense UV exposure of treated skin.

Safety

Who should avoid

Anyone taking prescription medicines — ask a doctor or pharmacist first (see interactions)
Pregnancy — NCCIH says it may raise the risk of birth defects; the EU regulator advises against
Breastfeeding — infants have had colic, drowsiness and lethargy
Under 18s — the EU regulator does not recommend it, too little data
Severe depression or suicidal thoughts — see a doctor rather than self-treating
Intense sun or sunbed exposure — photosensitive skin reactions, especially if fair-skinned
Before elective surgery — tell the surgical team, it may interact with anaesthetic drugs

Known interactions

AvoidBlood thinners — The EU regulator contraindicates use with coumarin-type anticoagulants (such as warfarin) because the herb induces CYP enzymes and can lower their levels; NCCIH lists warfarin among the medicines it weakens.

AvoidCancer treatment (chemotherapy) — The EU regulator contraindicates use with irinotecan, imatinib and other cytostatic agents cleared by CYP3A4, CYP2B6, CYP2C9, CYP2C19 or P-glycoprotein; NCCIH also names docetaxel among the medicines it weakens.

AvoidHormonal contraceptives — It lowers hormonal contraceptive levels, which the EU regulator says may cause breakthrough bleeding and reduced contraceptive safety, and advises additional contraceptive measures; NCCIH lists birth control pills among the medicines it weakens.

AvoidHIV medication — The EU regulator contraindicates use with indinavir, fosamprenavir and other protease inhibitors and nucleoside reverse transcriptase inhibitors; NCCIH names indinavir and nevirapine among the medicines it weakens.

AvoidImmunosuppressants — The EU regulator contraindicates use with cyclosporine, tacrolimus, sirolimus and everolimus, and a 2000 report of acute rejection in two heart transplant patients on cyclosporine started the interaction literature.

AvoidAntidepressants (SSRIs) — The EU regulator says it may add serotonergic effects with SSRIs such as sertraline and paroxetine, and very rarely serotonin syndrome (sweating, fast heart rate, fever, agitation, tremor); NCCIH says the extra effects can be serious.

CautionEpilepsy medication (anticonvulsants) — NCCIH says it can weaken some seizure drugs, naming phenytoin and carbamazepine, and describes such medicines as crucially important; the EU monograph does not name anticonvulsants.

CautionDigoxin & heart-rhythm medication — NCCIH says it can weaken digoxin and ivabradine, and the EU monograph advises special care with digoxin because its blood levels may fall.

CautionStatins (cholesterol medication) — NCCIH says it can weaken certain statins, including simvastatin, and the EU monograph advises special care with simvastatin because its blood levels may fall.

MonitorSedatives & sleep medication — The EU monograph names alprazolam, diazepam and midazolam among drugs whose blood levels may fall, advising special care; it reports no sedative-specific harm.

Questions people ask

Does St John's wort work as well as antidepressants?

For mild to moderate depression, the Cochrane review found extracts about as effective as standard antidepressants (response ratio 1.00 against SSRIs), with fewer dropouts from side effects. A large US trial in more severe depression found no benefit over placebo, and NCCIH says it is uncertain for severe depression or beyond 12 weeks.

Can I take St John's wort with the pill or other medicines?

Often not safely without advice. It speeds up how the body clears many drugs, and the EU regulator says it can reduce hormonal contraceptive levels and advises extra contraception. It is contraindicated with warfarin-type anticoagulants and several transplant and cancer drugs, so ask a doctor or pharmacist first.

Can I take St John's wort with an SSRI?

It is not advised. Both the EU regulator and NCCIH warn that the combination can add to serotonin effects, and the monograph describes rare cases of serotonin syndrome with sweating, fast heart rate, fever, agitation and tremor. Do not swap or stop an antidepressant yourself, and speak to the prescriber.

How long does St John's wort take to work?

The EU regulator says the effect can be expected within 4 weeks of treatment, so judge it after about a month, not a few days. If symptoms persist during use, see a doctor.

Sources

Last reviewed 29 September 2026 · Next review March 2027 · How we rate evidence