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St John's wort

Explains what St John's wort is, what it's used for and what side effects you might get. Also covers whether you can take it with other medications and how to stop taking St John's wort safely.

What is St John's wort and what's it used for?

St John's wort is a herbal medicine used to treat mental health 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.

Today St John's wort is mainly used as an over-the-counter remedy to treat mild and moderate depression.

Are there side effects and is it safe?

Some research shows that people who take St John's wort have fewer, or less serious, side effects than with commonly prescribed antidepressant medications. There are also some people who take St John's wort and do not have any side effects.

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

However, those who do have side effects most commonly report:

  • feeling nauseous or being sick
  • diarrhoea
  • headaches
  • allergic reactions
  • tiredness
  • dizziness
  • confusion
  • a dry mouth
  • skin problems
  • increased sensitivity to sunlight.

Some research also shows that St John's wort can increase psychotic symptoms in those of us with bipolar disorder or schizophrenia.

If you experience any side effects which you think should be reported, you can share your experiences with the Medicines & Healthcare products Regulatory Agency (MHRA) via their Yellow Card scheme.

Does it work?

Research suggests that St John's wort works in a similar way to standard antidepressant medication, by increasing the activity of brain chemicals such as serotonin and noradrenaline that are thought to play an important part in regulating our mood. In some cases, St John's wort might be just as effective as some antidepressant drugs to treat mild or moderate depression.

“I found that St John's wort lifted my mood so I wasn't waking up at 5am every morning. Life seemed more bearable. I saw colour.”

However, for severe depression there is little evidence to show that it could help. There also have not been many studies on whether it can work over a long period of time. 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 (SAD), it's worth noting that there's very little evidence on how effective it can be for these conditions. Some research suggests that it can make feelings of anxiety worse for some people.

What dosage should I take?

St John's wort is sold in a variety of different forms. The dosages available vary depending on the form and brand that you buy. It is most commonly sold as tablets and capsules. You can also get it as a tea, or as a liquid called a 'tincture', which you can take as drops in water.

All medicines carry levels of risk in different circumstances, and can affect people in different ways. There is no standard recommended dosage of St John's wort in the UK and it's not currently clear what dosage works best.

It's easiest to keep track of what dose you're taking if you take St John's wort in tablet or capsule form and if you stick to one particular brand. Be aware that if you buy a different type or brand, the dosage may be different or cause different side effects.

“My experience of St John's wort has been a bit negative. As it's a herbal medicine, you're never too sure if you're taking the right dose.”

If you are considering taking St John's wort, talk to your doctor or a pharmacist first to discuss what dosage would be best for you and check that it will not interact dangerously with any other medications you are taking.

Before deciding what dose to take, read the packaging carefully and consider:

  • How strong the product is. The packaging should give you an indication of this by describing the amount of hypericin or hypericum extract in the ingredients list or nutritional information section.
  • How many times you should take the product each day. Directions should be given on the packaging. Tablets and capsules typically range from 1-3 times a day, depending on their strength.

On the packaging of some products it might refer to the amount of St John's wort as 'aerial parts'. This just means the parts of the plant that grow above the ground.

“It's a good stop-gap solution to make you feel you're doing something to take control of depression. However, I've found the knock on effects of missing a dose to be worse than that of SSRIs.”

Can I take it with other medications?

St John's wort has significant interactions with a large number of medicines which are in common use.

This means that it may affect the way the body processes other medications, which may make them less effective, or increase the chances of harmful side effects. These medications include both prescribed drugs and medicines that you can buy for yourself over the counter.

If you're taking, or considering taking, St John's wort at the same time as any other medications (prescription or over-the-counter), it's really important to get professional advice from a pharmacist or your doctor.

They will be able to talk to you about any possible interactions St John's wort may have with your medications, and tell you about alternative treatments or dosages.

For example, if you are taking any of the following drugs, speak to your doctor before trying St John's wort:

  • antidepressants
  • antipsychotics
  • sleeping pills and anaesthetics
  • hormonal contraceptives (including emergency contraception)
  • anticoagulants (drugs that thin the blood)
  • immunosuppressants (drugs that prevent your immune system from damaging healthy cells)
  • cholesterol and heart disease medications
  • blood pressure medications
  • migraine medications
  • epilepsy medications
  • cancer treatments
  • HIV and AIDS treatments.

For a more detailed list of known medications that interact with St John's wort, you can visit the National Institute for Health and Care Excellence (NICE) website.

Where can I get St John's wort?

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 in the UK without a prescription, it is best to seek advice from your GP first. 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.

St John's wort is available on prescription in many European countries. However, the use of St John's wort is not currently recommended by the National Institute for Health and Care Excellence (NICE) so doctors in England and Wales do not normally provide it on prescription.

This is because of uncertainty about appropriate doses, variations in preparations and the potentially dangerous interactions that it has with other commonly used medications.

Although doctors are advised not to prescribe St John's wort, you can buy it over-the-counter. It is readily available in pharmacies and in many health food shops.

Will I get withdrawal symptoms from stopping?

As St John's wort works in a similar way to antidepressants, it's important to take similar care in stopping them as you would with antidepressants. It's a good idea to slowly reduce your dosage, as this reduces the chance of withdrawal symptoms. This is especially important if you've been taking it for longer than a few weeks.

If you are thinking about stopping taking St John's wort, it can be really useful to talk to your doctor about the safest way to withdraw. Some people stop taking St John's wort without any problems, while others experience withdrawal symptoms. Unfortunately, current information about withdrawal symptoms isn't very clear and more research needs to be done.

Those who do experience withdrawal symptoms tend to report feeling sick, dizzy and tense during the withdrawal period, especially if they stop taking it suddenly without slowly reducing their dose.

For tips on self-care while experiencing withdrawal symptoms have a look at our page on self-care during withdrawal.

“I had no side effects other than some photosensitivity and no withdrawal symptoms. Usually I am very side effect-sensitive so this was a great benefit.”

Where can I find out more?

For more information on St John's wort and herbal medicines in general see:

This information was published in January 2022. We will revise it in 2025.

References and bibliography available on request.

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