St John's Wort - Hypericum perforatum

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What is St John's wort?
History of St John's wort
Current uses
How does it work?
What are the side effects?
Is it always safe to take St John's wort?
Is it safe to take St John's Wort with other drugs?
What dosage should be used?
Useful contacts
Further reading
References

What is St John's wort?

The plant St John's wort has been used as a herbal remedy for a variety of ailments for centuries; currently it is most often used, in tablet form, to treat depression. The word 'wort' is pronounced to rhyme with 'word' (not 'wart'). 'Wort' forms part of the name of many medicinal herbs, such as lungwort, woundwort, soapwort etc.

Important note
Many people believe that as herbal remedies are 'natural', they are completely safe and free of side effects. This is not the case: many herbs are very poisonous (hemlock, for example), while other plants are poisonous in some parts and safe in others (such as the potato); however, extracts from poisonous plants may make very useful medicines when used in the right way (for example, digitalis, a heart drug which comes from foxglove). Of course there are some herbs that are both harmless and useful as medicines.

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History of St John's wort

The plant is named after St John the Baptist, whose feast day, 24 June (midsummer), occurs when daylight in Europe is longest and the plant is in full bloom. Its five yellow petals resemble a halo, and its red sap symbolises the blood of the martyred saint. The name Hypericum comes from the Greek, meaning 'greatest health'.

St John's wort has been used as a folk medicine for hundreds of years, particularly for healing wounds. In medieval times, St John's wort was used for 'driving out the inner devil'. The philosopher Paracelcus (c1525) recommended it for hallucinations and 'dragons', as well as for healing wounds.

Its antibacterial properties were reported scientifically in 1959 and 1971, when the active antibacterial substance, called hyperforin, was extracted and analysed. It is also known to be effective for treating viral infections such as herpes. [1]

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Current uses

Tablets made using a standardised extract of St John's wort have been extensively researched in Germany since the early 1980s, [2] and are now widely available from health food shops as a herbal remedy for mild to moderate depression. Research in America found it unhelpful for severe depression, [3] but this has been questioned by more recent research which suggests that it compared favourably with paroxetine (a synthesised antidepressant) in moderate to severe depression. [4]

There are products available combining St John's wort with other herbs, such as lemon balm (Melissa officianalis) and hops (Humulus lupulus), which are both sleep-inducing herbs. This combination would be suggested for people with depression who have difficulty sleeping.

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How does it work?

In addition to hyperforin (see 'History of St John's wort' above), research also focuses on hypericin as an active ingredient of the plant, but it contains many other substances which may contribute to its antidepressant activity in ways that are not understood. [5]

Scientific studies of the herb suggest that it acts to increase the activity and prolong the action of the brain chemicals serotonin and noradrenaline, in a similar manner to standard antidepressants, but with many fewer reported side effects.

What are the side effects?

The most commonly reported side effects of St John's wort include gastrointestinal symptoms (such as nausea, vomiting, diarrhoea), allergic reactions, fatigue, dizziness and confusion. Dry mouth occurs in a small percentage of patients. A rare side effect is increased sensitivity to sunlight; people taking it should increase their sun protection and avoid strong sunlight.

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Is it always safe to take St John's wort?

Patients with a diagnosis of bipolar disorder should use it with caution, since, as with all antidepressants, it has been known to cause hypomania (see Mind's factsheet Hypomania), or rapid switching from a low to a high mood.

You should not take St John's wort if you are pregnant or breastfeeding, because there is no information on its safety in these conditions. It should also not be used for children under the age of 16 for the same reason.

Is it safe to take St John's Wort with other drugs?

St John's wort has significant interactions with a large number of medicines which are in common use (in addition to those mentioned below). These are listed in the British National Formulary (BNF), [6] and include both prescribed drugs and over-the-counter medicines, such as paracetamol. People who are taking any other medicine should always seek professional advice from a pharmacist, medical herbalist or doctor before combining it with St John's wort.

• You should not take St John's wort at the same time as any other antidepressant.
• St John's wort may prolong the effects of some sleeping pills and anaesthetics. If you are to receive an anaesthetic you should tell the anaesthetist if you are taking St John's wort.
• It reduces blood levels of oral contraceptives, increasing the risk of pregnancy and breakthrough bleeding.

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What dosage should be used?

St John's wort is an unlicensed herbal medicine, and there is no standardisation of preparations or dosage. The German trials [7] (see 'History of St John's wort') appear to have used a daily dose of total extract, ranging from 0.4mg (400 micrograms) up to 1000mg (1 gram).

Preparations available in the UK often give a strength in terms of percentage hypericin, or hypericum extract, and the suggested dosage is 200mg to 1000mg of 0.3 per cent standardised hypericum extract per day, which is usually taken in two or three doses. [8]

It is important to check the strength and follow the dosage recommendations of the product you are using, and to be aware that if you switch to a different product the strength may be different.

Depending on the herbal composition of the product used, St John's wort may take effect more quickly than prescribed antidepressants. [9] (See Making sense of antidepressants.)

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Useful contacts

British Herbal Medicine Association
PO Box 583, Exeter EX1 9GX
tel: 0845 680 1134
email: secretary@bhma.info
web: www.bhma.info

National Institute of Medical Herbalists
Elm House, 54 Mary Arches Street, Exeter EX4 3BA
tel: 01392 426022
email: nimh@ukexeter.freeserve.co.uk
web: www.nimh.org.uk 
A list of NIMH members is available on this site.

Further reading

Mind booklets
How to improve your mental wellbeing
How to look after yourself
Making sense of antidepressants
The Mind guide to managing stress
Understanding anxiety
Understanding depression

Mind factsheets
Hypomania

Other publications (available from Mind Publications on 0844 448 4448 or Mind's online bookshop)
Manage your mind: the mental health fitness guide, G Butler and T Hope, OUP 2007
Overcoming depression, W Dryden and S Opie, Sheldon Press 2003

References
[1] http://maltawildplants.com/CLUS/Docs/HYPTQ/AntiViralProperties.htm accessed February 2008.
[2] Linde K .et al, 1996, 'St John's wort for depression – an overview and meta-analysis of randomised clinical trials', BMJ, vol 313, 3 August, pp 253-258. And Helmut Woelk for the Remotiv/Imipramine Study Group, 2000, 'Comparison of St John's wort and imipramine for treating depression: randomised controlled trial', BMJ vol 321; pp536-539.
[3] Barclay L, 2002, 'St John's wort no better than placebo for depression', www.medscape.com 
[4] Szegedi A, Kohnen R , Dienel A and Kieser M, 2005, 'Acute treatment of moderate to severe depression with hypericum extract WS 5570 (St John's wort): randomised controlled double blind non-inferiority trial versus paroxetine', BMJ, vol 330, 5 March, pp 503-506.
[5] Taylor D, Paton C and Kerwin R, 2007, The Maudsley Prescribing Guidelines 9th edition, Informa Healthcare. (p 244, St John's wort)
[6] British National Formulary, 54 2007, BMJ Publishing Group and RPS Publishing. www.bnf.org
[7] Linde K. et al, 1996, 'St John's wort for depression – an overview and meta-analysis of randomised clinical trials', BMJ, vol 313, 3 August, pp 253-258. And Helmut Woelk for the Remotiv/Imipramine Study Group, 2000, 'Comparison of St John's wort and imipramine for treating depression: randomised controlled trial', BMJ vol 321; pp536-539.
[8] Bazire S and Branch S, Users drug information text, Norfolk Mental Health Care NHS Trust,
www.nmhct.nhs.uk/Pharmacy/stjohnswort.htm, accessed February, 2008
[9] Keith Robertson, Director of Education at the Scottish School of Herbal Medicine, quoted on www.netdoctor.co.uk/special_reports/depression/stjwort.htm, accessed February 2008.

This factsheet was written by Katherine Darton. Updated, February 2008.