St John's wort
A flowering plant sold over the counter, taken above all for low mood.
- Low mood
- Menopause and hot flushes
- Memory and focus
A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.
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On this page
What is st John's wort?
St John’s wort is a perennial plant found across much of the world, and the part used is the leaves and flowering tops. It appears in Chinese, Greek and Islamic traditional medicine, where it has been used for centuries for minor burns, for anxiety and for low mood. Its best-known compounds are hypericin and hyperforin, and capsules and tablets are normally standardised to a stated percentage of hypericin, most often 0.3 per cent. In several European countries it is licensed and prescribed for depression; elsewhere people buy it over the counter for themselves.
Why do people take st John's wort?
Low mood
The thinking. Low mood is what nearly everyone takes St John’s wort for, and it is the use its research has followed for thirty years. In several European countries a doctor can prescribe it, so a shopper here is buying what is a prescription medicine elsewhere. The idea is that something in the plant acts on the same mood chemistry as prescription antidepressants.
What research has found. Reviews have pooled dozens of randomised trials in adults with mild to moderate depression, measuring standard depression scores. Against placebo, the largest reviews found more people responding; against a prescription antidepressant, scores came out much the same, with fewer side effects and fewer people dropping out. A twenty-six-week trial following responders found no clear difference at the end. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.
Menopause and hot flushes
The thinking. Women going through the menopause are the other large group who take it, usually for hot flushes and for the low mood that can arrive alongside them. Some of the research gives the extract on its own and some gives it in fixed mixtures with other herbs. The thinking is the same one as for mood, applied to a stretch of life that unsettles it.
What research has found. Two reviews and one trial have measured hot flushes and standard menopausal symptom scores. One review, pooling extracts alone and in mixtures with other herbs, found a clear advantage over placebo; a two-month trial in eighty postmenopausal women found hot flushes less frequent and less intense, and depression scores lower. A second review, looking at the plant beside two other herbs, found no better result than placebo. The studies disagree, so this is unsettled: dose, duration and who took part all seem to shift the result.
Memory and focus
The thinking. A smaller group take St John’s wort with work or study in mind, and products sold over the counter have been promoted on the argument that they sharpen memory and hold attention steady. The thinking leans on the same nervous-system effects as the mood use, and reviews also describe the plant’s compounds shielding nerve cells from damage in laboratory work.
What research has found. One trial gave eighty-two students a single dose and tested short-term memory and sustained attention the same day. The smaller of the two doses came out ahead of placebo on a memory-span test while the larger dose came out behind it, and both lifted mood scores. The authors put the difference down to the amount taken. Few studies have measured this yet, so there is little to go on either way.
What does st John's wort do in the body?
St John’s wort is not a nutrient the body runs short of; it is a plant carrying a mixture of active compounds. The two that draw most attention are hypericin and hyperforin, alongside xanthones and flavonoids. Reviews say plainly that no single mechanism explains what it does: several of its compounds act in ways that fit the mood research, but none accounts for the whole effect. Preparations low in hyperforin have done as well in depression trials as those carrying more.
What is clearer is what it does to everything else. Its compounds switch on a receptor in the liver and gut that turns up the body’s main drug-clearing enzyme, and a pump that pushes substances back out through the gut wall. A great many prescription medicines are cleared by that route, so they leave the bloodstream faster while someone is taking the plant. The more hyperforin a preparation carries, the stronger that effect is.
What do people say about taking st John's wort?
These are anecdotes people have shared, not evidence.
What people like
- Very commonly, a steadying of mood and less anxiety: people describe feeling calmer, more like themselves and able to cope with an ordinary day.
- Often it is described as gentler than a prescription antidepressant, with fewer side effects, which is why several say they reached for it first.
- Some take it for a low patch rather than long term: a hard winter, a bad stretch at work, and stop afterwards.
- A minority have taken it for years and say they notice the difference when they stop and feel it again when they restart.
Common complaints
- Interactions are raised more than anything else: in nearly every thread someone warns it makes the contraceptive pill less reliable, breakthrough bleeding included.
- Warnings about other prescription medicines are almost as common, usually alongside the point that being a plant does not make it mild.
- Sensitivity to sunlight comes up in several threads, and a few describe burning badly after very little time outdoors while taking it.
- Some report nothing at all, and others side effects of their own: upset stomach, headaches, acne, broken sleep, rarely a severe allergic reaction.
How people take it
- One tablet a day at the dose on the packet is the usual pattern; a few take two or three, spread through the day.
- People very commonly say it takes one to three weeks of daily use before anything shows, so patience is the advice given most.
- Buying a standardised extract rather than the cheapest tablet is advice repeated across threads, because posters say strength varies between products.
- Some pair it with another supplement such as magnesium or omega-3, and a few take it as a tea, which several call weaker.
Read from these public discussions:
- Anyone taking st johns wort ? (Mumsnet, 2011)
- To ask for people's experiences with St John's Wort (Mumsnet, 2020)
- Anxiety. St John's Wort (Mumsnet, 2020)
- St John's Wort - does it work?? (Mumsnet, 2021)
- Experience with St John's Wort? (Mumsnet, 2021)
- St Johns Wort? (Mumsnet, 2022)
What forms of st John's wort are there?
| Form | What’s different | Per serving, on products we list |
|---|---|---|
| St John’s wort (0.3% hypericin) | Extract of the leaves and flowering tops, standardised so that 0.3 per cent of it is hypericin. | 250 mg |
What else is worth knowing about st John's wort?
- St John’s wort changes how the body handles many prescription medicines. It switches on the enzymes and the gut pump that clear drugs away, so less of the medicine reaches the blood, and reviewers write that these interactions should be disclosed and considered before anyone uses it.
- The contraceptive pill is among the medicines affected, and so are the medicines taken after an organ transplant: one review opens with a case from 2000 in which two people rejected a transplanted heart after the two were taken together.
- Labels give the amount of extract per serving, and a serving may be more than one capsule; most also state the percentage of hypericin the extract is standardised to, usually 0.3 per cent.
- In the depression reviews, side effects were reported about as often as on placebo and less often than on a prescription antidepressant, though the trials were not built to pick up rare ones. They ran from four to twelve weeks, so the longer-term picture is not covered, and reviewers say severe depression has not been studied.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
The research behind this page (14 studies)
- The efficacy and safety of St. John's wort extract in depression therapy compared to SSRIs in adults: A meta-analysis of randomized clinical trials. (2023, meta-analysis)
- Clinical use of Hypericum perforatum (St John's wort) in depression: A meta-analysis. (2017, meta-analysis)
- A systematic review of St. John's wort for major depressive disorder. (2016, meta-analysis)
- St John's wort (Hypericum perforatum) versus sertraline and placebo in major depressive disorder: continuation data from a 26-week RCT. (2012, randomised trial)
- Hypericum perforatum L. preparations for menopause: a meta-analysis of efficacy and safety. (2014, meta-analysis)
- Efficacy of Cimicifuga racemosa, Hypericum perforatum and Agnus castus in the treatment of climacteric complaints: a systematic review. (2012, systematic review)
- The effect of Hypericum perforatum on postmenopausal symptoms and depression: A randomized controlled trial. (2019, randomised trial)
- The acute effect of Hypericum perforatum on short-term memory in healthy adults. (2019, randomised trial)
- Clinical relevance of St. John's wort drug interactions revisited. (2020, review)
- Hypericum perforatum : Traditional uses, clinical trials, and drug interactions. (2022, review)
- Elicitation as a tool to improve the profiles of high-value secondary metabolites and pharmacological properties of Hypericum perforatum. (2019, review)
- Neuroprotective Activity of Hypericum perforatum and Its Major Components. (2016, review)
- Hypericum perforatum: pharmacokinetic, mechanism of action, tolerability, and clinical drug-drug interactions. (2014, review)
- Hypericum perforatum (St John's wort) beyond depression: A therapeutic perspective for pain conditions. (2017, review)
How much does st John's wort cost?
That depends on the form and the pack, so we work out the price of the same dose of every st John's wort product we can find and rank them.