A: St John's Wort is the most common herbal therapy used for depression and is especially popular in Europe. In North America, it's sold as a dietary supplement and is available without a prescription. This herbal extract (derived from the flowering plant called Hypericum perforatum) has some of the same biologic properties as synthetic antidepressants and works by inhibiting the synaptic reuptake of neurotransmitters.

While some studies have demonstrated that St. John's Wort can be effective for treating mild to moderate depression, there is not enough evidence to conclude that it's effective for major depression. This product is widely available in pharmacies and natural food stores, making it easy to obtain and increasing the perception that it is safe and effective.

Despite its popular use, there is not enough information to recommend using St. John's Wort during your pregnancy. There are no clinical trials examining its safety during pregnancy. The limited information we have comes from animal studies and a few isolated reports of women who have taken St. John's Wort during pregnancy.

The effects of St. John's Wort on a developing baby are largely unknown. Of the two case reports of clinical use during pregnancy, there were no birth defects noted, but one woman had a low platelet count and her baby had neonatal jaundice. One study suggested higher rates of colic, drowsiness and lethargy in nursing infants whose mothers used St. John's Wort. Animal studies have not revealed delays in growth or cognition from prenatal exposure, but one recent study found liver and kidney damage in offspring of rat mothers given St. John's Wort during pregnancy and lactation.

You should also be aware that St. Johns Wort has side effects and can interact with other medication. Adverse effects include nausea, restlessness, dizziness, dry mouth and constipation. It can also make your skin more sensitive to light (photosensitivity). St John's Wort also induces the liver to produce an enzyme that can interfere with the processing of other medications.

If you are feeling depressed, please talk to a health care provider about your concerns. You may find that therapy can be helpful during this period of your life. Any medication that you take, including herbal preparations, should only be used after consultation with a medical professional.