It has been used since ancient Greece for neurological conditions, both physical and emotional. It was used to treat sciata, hip pain, and burns, as well as malaria, wounds, burns, and ulcers. In the 1800’s, it was used to treat a variety of emotional disorders, and was classified as a "nervine". It has been rigorously studied, and in fact is the most well researched herb. It has undergone such significant scrutiny that in Germany it is considered a prescription medication, and covered by insurance as such. It has been used in Germany for mild depression for many years.¹

While relatively "new" in the United States, patients may show a marked improvement in as little as one week – far sooner than with most prescription medications. In addition, St. John’s Wort has far fewer side effects (mainly light sensitivity in fair-skinned patients). There may also be some interaction with medications used in treating HIV. In some cases, patients respond as well to St. John’s Wort as to prescription medications.²

St John’s Wort contains several flavonoids (including Quercetin) and the napthodianthrones hypericin and pseudohypericin, all of which appear to have medicinal properties. However, it appears from recent research that the hyperforin component of St. John’s Wort may actually be the compound with the major antidepressant activity. The precise mechanism of action is not known; there is some evidence that it functions as an MAO inhibitor, but other research indicates that it may also function to block serotonin reuptake.^3,4

St. John’s Wort, in addition to treating depression, also has been shown effective in the treatment of mild anxiety⁵

Useful in treatment of:

• Depression: There are numerous studies documenting the efficacy of St. John’s Wort in treating mild to moderate depression. It also appears to compare favorably to standard prescription medications for mild depression. It is not indicated for the treatment of severe depression.^4,6,7,8,9
• Anxiety: Many of the studies on depression document a beneficial effect on anxiety as well.
• Seasonal Affective Disorder: One small study found that St. John’s Wort was beneficial in SAD, a mild depression that occurs primarily in the winter months. ¹⁰

Recommended Dosage: Varied, however most studies have used 300mg of an extract standardized to 0.3% hypericin. More recent literature suggests that the extract be standardized to 3% hyperforin, for a total daily dose of 27 mg of hyperforin per day (typically divided in 3 doses).

Contraindications: May cause light sensitivity in fair-skinned individuals.

Drug Interactions: Consult with your qualified physician before starting St. John1s Wort; especially if you are taking any of the following medications: Antidepressant drugs, such as MAO inhibitors, SSRIs, and tricyclics; or possibly the drug tramadol: St. John's wort should not be used at the same time. You must let the medication get cleared from your system (up to several weeks in some cases) before you start the herb.

St. John's wort might have an additive effect on the following medications: sulfa drugs (and others that may cause sun sensitivity), the anti-inflammatory medication Feldene (piroxicam), as well as proton pump inhibitors such as Prilosec (omeprazole) or Prevacid (lansoprazole.

St. John's wort appears to be an inducer of an important metabolic pathway, cytochrome P450. As many prescription drugs used to treat conditions such as heart disease, depression, seizures, certain cancers or to prevent conditions such as transplant rejection or pregnancy (oral contraceptives) are metabolized via this pathway, health care providers should alert patients about these potential drug interactions to prevent loss of therapeutic effect of any drug metabolized via the cytochrome P450 pathway. Therefore, St. John's wort might cause the following drugs (and drugs similar to these) to be less effective. Digoxin, cyclosporine, protease inhibitors (for HIV infection), oral contraceptives, amitriptyline, Coumadin (warfarin), theophylline, chemotherapy drugs, or, indeed, any critical medication.

References:

¹St John's wort for depression--an overview and meta-analysis of randomised clinical trials [see comments] BMJ, 313(7052):253-8 1996 Aug 3
²Vorbach EU, Hubner WD, Arnoldt KH. Effectiveness and tolerance of the Hypericum extract LI 160 in comparison with imipramine: Randomized double-blind study with 135 outpatients. J Ger Psyciatr Neruol 1994;7(Suppl 1):S19–23.
³Baureithel KH, Buter KB, Engesser A, et al. Inhibition of benzodiazepine binding in vitro by amentoflavone, a constituent of various species of Hypericum. Pharm Acta Helv 1997;72:153–57.
⁴Laakman G; Schule C; Bagahai T; Kieser M. St. John's wort in mild to moderate depression: The relevance of hyperforin for the clinical efficacy. Pharmacopsychiatry 31(Suppl.): 54–59, 1998.
⁵Baureithel KH, Buter KB, Engesser A, et al. Inhibition of benzodiazepine binding in vitro by amentoflavone, a constituent of various species of Hypericum. Pharm Acta Helv 1997;72:153–57.
⁶Linde K, et al. St. John's wort for depression—An overview and meta-analysis of randomized clinical trials. BMJ 313: 253–258, 1996.
⁷Ernst E. St. John's wort, an anti-depressant? A systematic, criteria-based review. Phytomedicine 2(1): 67–71, 1995.
⁸Harrer G, et al. Comparison of equivalence between the St. John's wort extract LoHyp-57 and fluoxetine. Arzneimittelforschung 49: 289–296, 1999.
⁹Philipp M, et al. Hypericum extract versus imipramine or placebo in patients with moderate depression: randomised multicentre study of treatment for eight weeks. BMJ 319: 1534–1539, 1999.
¹⁰Martinez B, et al. Hypericum in the treatment of seasonal affective disorders. J Geriatr Psychiatry Neurol 7(Suppl. 1): 29–33, 1994