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 the United States, 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.
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 U.S. Food and Drug Administration (FDA) does not regulate dietary supplements in the same way it regulates medicines. A dietary supplement can be sold with limited or no research on how well it works.
Always tell your doctor if you are using a dietary supplement or if you are thinking about combining a dietary supplement with your conventional medical treatment. It may not be safe to forgo your conventional medical treatment and rely only on a dietary supplement.
When using dietary supplements, keep in mind the following:
- Like conventional medicines, dietary supplements may cause side effects, trigger allergic reactions, or interact with prescription and nonprescription medicines or other supplements you are taking. A side effect or interaction with another medicine or supplement may make other health conditions worse.
- Dietary supplements 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 dietary supplements, other than vitamins and minerals, are not known. Many dietary supplements are not used long-term.