This information explains what St John's wort is used for, how it works, possible side effects and interactions with other medicines.
Even though herbal remedies are natural, this doesn't mean that they are always safe and free of side effects. It is really important to think about this if you are already taking any other medication.
See our page on St John's wort interactions for more information.
Some people who take St John's wort do not report any side effects. However, those who do have side effects most commonly report:
A rare side effect of St John's wort is increased sensitivity to sunlight. If you think this is affecting you, you should consider using a high factor sunscreen, cover up your skin or stay out of the sun as much as possible. It is also best to talk to a doctor before trying light therapy for seasonal affective disorder (SAD), as St John's wort can make your skin more sensitive to light.
"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."
If you experience any side effects which you think should be reported, you can report them to the Medicines and Healthcare Products Regulatory Agency (MHRA) via their Yellow Card system.
As St John's wort has similar properties to prescribed antidepressants, it is advisable to slowly reduce your dosage to lessen the chance of withdrawal symptoms, especially if you have 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 to discuss the safest methods to withdraw.
Some people stop taking St John's wort without any problems, while others experience withdrawal symptoms. Unfortunately, current information about withdrawal symptoms is limited and inconsistent.
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.
This information was published in January 2020. We will revise it in 2023.
References are available on request. If you would like to reproduce any of this information, see our page on permissions and licensing.