What is St John's wort?

In short

St John's wort is a plant with yellow flowers. Its extracts contain plant compounds including hypericin and hyperforin.

Too much

St John's wort can reduce the effects of many medicines, including blood thinners and the contraceptive pill. Unintended pregnancies are possible. Taking it with antidepressants can cause a dangerous excess of serotonin. If you take medicines, speak to your doctor before taking it. St John's wort can make your skin more sensitive to sunlight.

Interactions

• St John's wort and Antidepressants

  St John's wort together with antidepressants can cause a dangerous excess of serotonin. Only after talking to your doctor.

• St John's wort and Blood thinners

  St John's wort can weaken the effect of blood thinners. Only after talking to your doctor.

• St John's wort and Contraceptive pill

  St John's wort can make the pill ineffective. Unwanted pregnancies are possible. Only after talking to your doctor.

Other names

Hypericum perforatum, Echtes Johanniskraut, Tüpfel-Johanniskraut, St John's wort, Hipérico, Hierba de San Juan

Source

EMA: EU herbal monograph on Hypericum perforatum L., herba.