Swallowed or applied to the skin, St John's Wort, botanical name Hypericum perforatum, is basically safe. However, it can create a range of adverse reactions for people suffering from a variety of conditions such as hypertension or blood pressure. It can also make antiviral, HIV, or antidepressant medications ineffective.
Russell Setright, Blackmores Naturopathic Director, emphasises that St John's Wort has an excellent safety profile but he warms people who are taking the herb should inform their professional health practitioner so their drug dosage can be adjusted to determine the safety of its effects in combination with other medication.
If someone is concurrently taking selective serotonin reuptake inhibitors (SSRIs) with St John's Wort, there may be a need to discontinue the herbal medicine while undergoing this type of drug therapy, Russell says.
Rebecca Gouldhurst, a naturopath and private practitioner, agrees that the combination of antidepressant medication and St John's Wort can over stimulate the serotonin.
Although it is not addictive, Rebecca believes this feel good herb, which stimulates the serotonin receptors and has a restorative effect on the nervous system, can create a variety of similar side effects as some recreational drugs or exercise. It releases the endorphins, Rebecca says.
Another combination calling for caution is St John's Wort and drugs such as oral contraceptives, HIV protease inhibitors, and certain anticonvulsants. They can be a volatile cocktail.
Despite these warnings, Rebecca recommends the use of St John's Wort. It can be safely used to relieve anxiety, tension and irritability, particularly when these symptoms have persisted long enough to lead to fatigue and depression. Its also used for PMT, menopausal and postnatal depression, as well as other related symptoms.
However, Rebecca stresses another, lesser known possible risk. You can more sensitive to the sun when you take St John's Wort so you have to avoid excessive sunlight.
If there's any doubt, Rebecca says, St John's Wort should be avoided unless consultation has been sought from a medical practitioner.
According to a recent paper written by Hans Wohlmuth, lecturer in Pharmocognosy, School of Natural and Complementary Medicine, Southern Cross University, NSW, St John's Wort can create some adverse outcomes in HIV-infected individuals, leading to the development of drug resistance and treatment failure.
The paper also questions the herb's interaction with SSRIs such as fluoxetine.
The answer: We don't know but it can't be rule out.
Another report outlined in the same paper details cases of elderly patients who combined St John's Wort with antidepressants resulting in gastrointestinal disturbances, tremor, headaches, restlessness and changes in mental status.
Available as a cream, tincture, tablet or capsule or as a liquid extract the herb St John's Wort is a native plant of Europe, North America and Asia. Found in alpine conditions, it grows to 90cm in height and has bright yellow, five-petalled flowers with numerous stamens.
The plant is harvested shortly before or during the flowering period. The red oil, made from the flowers, has local analgesic and slightly antiseptic effects. It is also astringent and promotes healing of wounds when used externally on the skin.
As a cream, it helps to relieve the pain of light burns, neuralgia, fibrositis (inflammation of the muscle fibres) and sciatica.
It can interact with a range of drugs, but this does not diminish the fact that St John's Wort is an effective treatment for a wide range of ailments and conditions. It has far more benign side effects than comparable pharmaceutical drugs, but it should be monitored carefully.