St John's Wort (Latin name: Hypericum perforatum) is a small plant with a yellow flower that grows wild in Australia and many parts of the world. It is a traditional herbal remedy in Europe, but has only recently been studied scientifically as a treatment option for depression.
The way St John's wort works is not fully understood. However, it is thought to increase the level of chemical messengers (neurotransmitters) in the brain that are thought be in low supply in depressed people.
There have been many studies comparing the effectiveness of St John’s Wort with placebos (dummy pills) and standard antidepressant medication. A systematic review of these studies has shown that St John’s wort works about as well as antidepressant drugs for people with mild to moderate depression. It is also found that St John’s Wort had fewer side effects than antidepressants. St John’s Wort may not be as effective as antidepressant medication for people with more severe depression.
A problem with herbal remedies compared to manufactured drugs is that the dose of the active ingredients cannot be precisely controlled. Like all drugs, St John's Wort can have side effects – these may include insomnia, agitation and sleep problems. However, people taking St John’s Wort generally experience fewer side effects compared to those taking standard antidepressant medication.
It is important to know that St John's Wort can interact with a number of other medicines. It can reduce the effects of these medicines, or increase their effects once St John's Wort is stopped. St John's Wort should not be taken in combination with any medication prescribed by your doctor for depression. If you are taking any other medication, whether it is for depression or any other condition, check with your doctor before taking St John’s Wort.
St John's Wort is sold in tablet form at health food shops, pharmacies and many supermarkets. St John's Wort is also sometimes added to food products (such as herbal tea or breakfast cereal), but there is no evidence that it is effective in this form.
If you do not want to use an antidepressant drug prescribed by a doctor, and you do not have severe depression, St John's wort might be a useful alternative.
Last reviewed and updated: 1 December 2016