The herb s active ingredients include hypericin, flavonoids , and other compounds that work in unison to raise serotonin levels in the brain, says Jennifer Brett, N.D., a naturopathic doctor at the Wilton Naturopathic Center in Stratford, Connecticut. While it s not understood exactly how the herb increases serotonin levels, researchers speculate that the underlying mechanism is probably similar to that of the prescription drugs, says Dr. Brett. St. John s wort may inhibit an enzyme that breaks down serotonin molecules and other brain chemicals, or it may increase the action of serotonin at the nerve endings in the brain. The serotonin is available so that your brain can further utilize it to regulate your moods and emotions more effectively, she says. The advantage of St. John s wort over the prescription antidepressants is that it s associated with very few side effects.
Some people do get mild stomach irritation, and others have reported sun sensitivity and insomnia.
If you are pregnant, check with your doctor before taking this or any other supplement. If you are already taking antidepressant medication, you should also talk to your doctor before taking St. John s wort . Dr. Shealy suggests taking one 300-milligram tablet or capsule three times a day with meals if you have mild to moderate depression. For maximum effectiveness, buy a standardized extract containing 0.3 percent hypericin, he says. If you don t feel better after four to six weeks, it s unlikely to help, he adds.