St. John's wort flowers around the end of June, near the feast of St. John the Baptist. Apparently that's where the name originated. The herb is also known as goatweed, hypericum perforatum L. and Klamath weed.
Whatever you call it, you may find that taking St. John's wort helps to relieve depression, though research about this possible benefit has been undecided, according to the National Institutes of Health: National Center for Complementary and Alternative Medicine (NCCAM) website.
A study by the NCCAM and the National Institute of Mental Health concluded that St. John's wort was not found to be effective as an antidepressant. The same study also found that antidepressant medication was no more effective than St. John's wort as compared to a placebo.
The Mayo Clinic differs concerning the efficacy of St. John's wort for depression. According to an article on the Mayo Clinic website, studies have shown that mild to moderate major depression can be as successfully treated with St. John's wort as with tricyclic antidepressants. The studies were not conclusive as to whether or not St. John's wort is as successful as selective serotonin reuptake inhibitors (SSRI) antidepressants.
The Mayo Clinic website went on to report favorably concerning twenty years of research in Europe. The article concluded that studies lasting one to three months indicated that St. John's wort performs better than placebo, and as well as tricyclic antidepressants for mild to moderate major depression. These studies posit that St. John's wort may be more successful than SSRIs for this type of depression.
St. John's wort may be useful for somatoform disorders (psychiatric as opposed to physical disorders). This may not be the case for anxiety disorders.
Research is delving into the possibility that St. John's wort may help in treatment of mild to moderate atopic dermatitis, as well as neuropathic or nerve pain.
The Mayo Clinic recommended adult dosage of between 900 and 1800 mg of St. John's wort extract per day, taken orally. For children, the recommended dose is between 150 and 1800 mg of the extract taken orally.