St. John's Wort

The name St. John's Wort dates back to legends of John the Baptist. The herb is derived from a yellow flower native to Europe and Asia. European colonists brought St. John's Wort to North America where it is classified as a weed in spite of its averred medical benefits.
St. John's Wort was used by the Native Americans to end unwanted pregnancies. When ingested, some reported that St. John's Wort had the ability to induce abortion, in the right dose. (Warning: do not use St. John's Wort to induce abortion). The Native Americans also used a compound made of St. John's Wort topically to treat inflammation and to clean dirt from wounds.
Today St. John's Wort is popularly used to treat depression. The clinical studies for St. John's Wort's efficacy as an anti depressant vary wildly. Some find it largely more effective than placebos while others place the two equally. Nevertheless, homeopathic practitioners often employ St. John's Wort for mildly and severely depressed patients. In Germany St. John's Wort is more often prescribed than pharmaceuticals.
Why St. John's Wort works is largely a mystery. Doctors theorize that the herb inhibits serotonin re-uptake (by not allowing the brain to soak up the naturally-occuring pleasure inducing chemical serotonin, re-uptake inhibitors allow the brain more happy time with a higher amount of the chemical available). If this is true, then St. John's Wort works just like prescription anti depressants.
St. John's Wort can cause dizziness, confusion, and stomach pains. Some report increased apathy during its use. Rare incidences have been reported where subjects experienced increased sensitivity to light, getting sunburns in unlikely situations. It is believed that St. John's Wort may reduce fertility. Patients sometimes also experience painful withdrawal symptoms when they stop using St. John's Wort, even when they did not benefit from the herb.
St. John's Wort has an unusually large number of interactions with various drugs. The most common one is that St. John's Wort makes the drug less effective. This is thought to be because St. John's Wort affects liver chemistry in such a way as to detoxify the drug and clear it out of the system faster.
St. John's Wort should only be taken under medical advice if you are taking any other medication; also it should probably not be taken in the case of any disturbance of brain function (depression, bipolar disorder, epilepsy for example) except under medical supervision.
For these purposes recommended dosages must be followed. As with all herbs, excessive use leads to negative side effects. Make sure not to use the herb for long periods of time and always follow dosage instructions.