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St. John's Wort

Treatment Overview

St. John's wort (Hypericum perforatum) is a plant that people in European countries have used for centuries as a medicine for problems like depression. In Canada, it is sold as a dietary supplement.

Why It Is Used

Some people use St. John's wort to help with anxiety, depression, menopausal symptoms, or other conditions, such as seasonal affective disorder. There isn't clear proof from science that taking St. John's wort helps with these or other conditions.

Risks

St. John's wort may cause side effects, such as stomach upset, dizziness, fatigue, or a rash with sun exposure.

St. John's wort may interact with many medicines, such as antidepressants, birth control pills, blood thinners, cancer medicines, and heart medicines. Check with your doctor or pharmacist before taking this supplement.

St. John's wort shouldn't be taken while you're pregnant or breastfeeding.

The Natural and Non-Prescription Health Products Directorate (NNHPD), within the Health Products and Food Branch of Health Canada, regulates natural health products in Canada. Natural health products, including St. John's wort, must be reviewed and approved by the NNHPD before they can be sold in Canada.

Always tell your doctor if you are using a natural health product or if you are thinking about combining a natural health product with your conventional medical treatment. It may not be safe to forgo your conventional medical treatment and rely only on a natural health product.

When using natural health products, keep in mind the following:

  • Like conventional medicines, natural health products may cause side effects, trigger allergic reactions, or interact with prescription and non-prescription medicines or other natural health products you are taking. A side effect or interaction with another medicine or natural health product may make other health conditions worse.
  • Natural health products may not be standardized in their manufacturing. This means that how well they work or any side effects they cause may differ among brands or even within different lots of the same brand. The form you buy in health food or grocery stores may not be the same as the form used in research.
  • The long-term effects of most natural health products, other than vitamins and minerals, are not known. Many natural health products are not used long-term.

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