St. John’s wort
a perennial flowering plant, Hypericum perforatum, that has an extensive history of folk use, particularly as a sedative, a treatment for nerve pain and malaria, and a balm for wounds, burns, and insect bites. It is currently a highly popular product used in the treatment of mild to moderate depression, anxiety, and insomnia. There is some research supporting its effectiveness for these purposes, but studies have not demonstrated the superiority of St. John’s wort over placebo in the management of major depression. There is also some research suggesting that the herb possesses anti-inflammatory and antioxidant properties. The active agents are presumed to be hypericin and related compounds. Hypericin is known to exert some effects common to other antidepressants, such as inhibition of the reuptake of norepinephrine, dopamine, and serotonin. It may also exert some effects by modulating the neurotransmitters gamma-aminobutyric acid (GABA) and
glutamate. The agent should be used with caution, as it may interact adversely with or limit the effectiveness of a number of other drugs, particularly those used to treat HIV/AIDS and cancer and to prevent transplant rejection. It may also lead to serotonin syndrome if taken with other serotonergic antidepressants. Taken on its own, its side effects are rare but may include dry mouth, dizziness, diarrhea, nausea, increased sensitivity to sunlight, and fatigue.