St John's wort - Hypericum perforatum

This information explains what St John's wort is used for, how it works, possible side effects and interactions with other medicines.

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What is St John's wort?

St John's wort is a herbal remedy that has been used for hundreds of years to treat mental health problems. Today it is mainly used as an over-the-counter remedy to treat mild and moderate depression, and sometimes seasonal affective disorder (SAD), mild anxiety and sleep problems.

The botanical name for St John's wort is Hypericum perforatum, and it is sometimes marketed and sold as 'Hypericum'. It contains many active substances, including hypericin and hyperforin, which are thought to affect mood.

How does St John's wort work?

It is thought that St John's wort works in a similar way to standard antidepressant medication. Research suggests that it increases the activity of brain chemicals such as serotonin and noradrenaline that are thought to play an important part in regulating our mood.

Can St John's wort help me?

If you experience depression or low mood, you may decide to try St John's wort as a herbal alternative to antidepressants. While you can buy St John's wort from a pharmacy without a prescription, it is best to seek advice from your GP in the first instance. If you have any worries about your mental health and are unsure about treatment options, it is always useful to talk this through with your doctor before you make a decision.

"When I could no longer take SSRI's due to side-effects, I tried St John's wort as an alternative. It has definitely helped with my depression and my mood has lifted quite a lot."

Research suggests that, in some cases, St John's wort might be just as effective as some antidepressant drugs to treat mild or moderate depression. It may also cause fewer or less intense side effects than commonly prescribed antidepressants. However, for severe depression there is little evidence to show that it could help. Experiences vary from person to person and more research needs to be done.

If you are thinking about taking St John's wort to treat other mental health problems, such as anxiety or seasonal affective disorder, it is worth noting that there is very little existing evidence on how effective it can be.

"I found that St John's wort lifted my mood so I wasn't waking up at five every morning, life seemed more bearable, I saw colour."

Speak to your doctor first about taking St John's wort if you:

are pregnant or are breast feeding – there is limited information on its safety
have a diagnosis of bipolar disorder – as with all antidepressants, it has been known to cause hypomania in some people, or rapid switching from a low to a high mood
are under 18 – there is limited information on its safety
are currently taking prescribed medication, contraceptive medication (such as the pill) or common over the counter medications. See our page on interactions with medication for more information.