Got a case of the blues? St. John's wort just might help you.

For over 2,000 years, St. John's wort has been used in folklore and ancient medicines around the world. Today, the herb is used for the short-term treatment of mild to moderate cases of depression, anxiety, sleep disorders, and other emotional illnesses.

St. John's wort also has been used in the treatment of fluid retention and hemorrhoids, as well as being applied topically in the treatment of skin inflammation, skin wounds, burns, and nerve and muscle pain.

It is not entirely clear how St. John's wort works to treat depression.

"The herb contains many chemical compounds that elevate some neurotransmitters in the brain affecting a person's mood," says Nicole Nisly, MD, who heads the UI Hospitals and Clinics Complementary and Alternative Medicine Clinic.

The herb was initially studied as an alternative to prescription antidepressants with fewer side effects. However, side effects do exist such as light-sensitivity, dry mouth, stomach irritations, dizziness, and tiredness.

Nisly also warns that St. John's wort has been shown to interact with other drugs you may be taking, causing some drugs to metabolize too quickly through your body, making them less effective.

St. John's wort is usually sold in liquid or powder form and is found at most pharmacies and health food stores. As always, be sure to contact your physician before trying St. John's wort to make sure it does not interact with any other medications you are currently taking. If you are suffering from severe depression, you should consult your physician before trying St. John's wort.