Your questions about complementary medicines answered: St John's wort

This is the fifth article in a series providing evidence-based answers to common questions about complementary medicines from consumers and healthcare professionals.

[Extract]

What is St Johns wort?

Extracts of St John’s wort (SJW) or Hypericum perforatum, a perennial herb with small yellow flowers, are widely available in pharmacies and health food stores. Historically, SJW has been used for a variety of conditions including abdominal pains, alcoholism, earaches and menopausal complaints. However, the most common reason for using SJW is depression and low mood. Patients will commonly be advised to take SJW when presenting to health food stores with symptoms of depression. While high-quality, controlled studies found it to be effective for the treatment of mild-to-moderate depression, it has not been included in mainstream treatment guidelines because of uncertainty about appropriate doses, persistence of effect, variation in the nature of preparations and potentially serious drug interactions