St John's Wort (Hypericum)

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What is St John's wort?

St John's wort (hypericum) is a short, yellow-flowering, wild-growing plant. It has been used for centuries as a medicinal herb.

Extracts of St John's wort are made into capsules and other types of preparations which are used to treat depression. It recently became a popular treatment for depression.

How does St John's wort work?

St John's wort contains many different chemicals. Some are thought to be the active ingredients. How these chemicals actually work in the body is not clear. It is thought that they may alter the balance of some of the chemicals in the brain (neurotransmitters) such as serotonin, dopamine, gamma aminobutyric acid (GABA), and noradrenaline. Alterations in the balance of these neurotransmitters are thought to play some part in causing depression.

Antidepressants and depression

Sometimes a life problem such as bereavement, redundancy, illness, etc, may trigger a depression. Sometimes there is no apparent cause for a depression. However, antidepressants such as St John's wort treat the symptoms of depression, whatever the cause.

Symptoms of depression include: low mood, feelings of sadness, sleep problems, poor appetite, irritability, poor concentration, decreased sex drive, loss of energy, guilt feelings, headaches, aches, pains, and palpitations. If symptoms are eased, you not only feel better, but you may also be able to cope better with any problems or difficult circumstances.

How effective is St John's wort?

It is not clear how well St John's wort works in depression. A recent systematic review of St John's Wort (that reviewed many research trials) concluded that ...

"Current evidence regarding hypericum extracts is inconsistent and confusing. In patients who meet criteria for major depression, several recent placebo-controlled trials suggest that the tested hypericum extracts have minimal beneficial effects while other trials suggest that hypericum and standard antidepressants have similar beneficial effects."

So, St John's wort may have some effect on easing depression in some cases. It may be worth a try if you have mild depression. However, it is probably not appropriate to buy it 'over the counter' if you have moderate or severe depression. Generally, you should see a doctor for advice on treatment if you have moderate or severe depression.

How quickly does St John's wort work?

Like prescription antidepressants, it takes 2-4 weeks for the effect of St John's wort to build up fully.

Are there any side-effects or risks when taking St John's wort?

Some people think that because St John's wort is 'natural' then it is totally safe. This is not true as it contains many chemicals which sometimes cause problems.

Possible side-effects
The most common side-effects are dry mouth, dizziness, gut symptoms, increased sensitivity to sunlight, and tiredness.

Possible risks
St John's wort sometimes reacts with other drugs. So:

• You should not take it if you are taking warfarin, cyclosporin, oral contraceptives, anticonvulsants, digoxin, theophylline, or certain anti-HIV drugs. This is because it may reduce the effect of these drugs.
• You should not take it at the same time as taking an SSRI antidepressant (selective serotonin reuptake inhibitor) or a triptan drugs used for migraine (such as sumatriptan). This is because it has an additive effect to these drugs which can cause problems.

Also, you should not take St John's wort if you are pregnant or breastfeeding as it has not been proved to be safe in these situations.

Because of the uncertain effectiveness, possible side-effects, and possible interactions with other drugs, many doctors now do not recommend that St John's wort should be used. Also, if you have moderate or severe depression, it is generally best that you see a doctor who can advise on treatments and monitor your progress.

© EMIS and PIP 2006   Updated: June 2006   PRODIGY Validated

The authors and editors of this article are employed to create accurate and up to date content reflecting reliable research evidence, guidance and best clinical practice. They are free from any commercial conflicts of interest. Find out more about updating.

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