Common name: Klamath weed

Botanical name: Hypericum perforatum

Parts used and where grown: St. John's wort is found in Europe and the United States. It is especially abundant in northern California and southern Oregon. The above-ground (aerial) parts of the plant are gathered during the flowering season.

St. John's wort has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating	Health Concerns
	Depression
	Seasonal affective disorder
	Anxiety, Cold sores, Ear infections (recurrent), Infection, HIV support, Menopause, Ulcerative colitis, Wound healing
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Historical or traditional use (may or may not be supported by scientific studies): In ancient Greece, St. John's wort was used to treat many ailments, including sciatica and poisonous reptile bites. In Europe, St. John's wort was used by herbalists for the topical treatment of wounds and burns. It is also a folk remedy for kidney and lung ailments as well as for depression.

Active constituents: The major constituents in St. John's wort include hypericin and other dianthrones, flavonoids, xanthones, and hyperforin. While it was previously thought the antidepressant actions of St. John's wort were due to hypericin and the inhibition of the enzyme monoamine oxidase, current research has challenged this belief, focusing on other constituents, such as hyperforin, and flavonoids. Test tube studies suggest that St. John's wort extracts may exert their antidepressant actions by inhibiting the reuptake of the neurotransmitters serotonin, norepinephrine, and dopamine. This action is possibly due to the constituent hyperforin. St. John's wort is able to act as an antidepressant, by making more of these neurotransmitters available to the brain.

How much is usually taken ? The standard recommendation for mild to moderate depression is 500-1,050 mg of St. John's wort extract per day. Results may be noted as early as two weeks. Length of use should be discussed with a healthcare professional. For more severe depression, higher intakes may be used, under the supervision of a healthcare professional.

Are there any side effects or interactions ? St. John's wort has a low incidence of side effects compared to prescription antidepressants. An adverse events profile of St. John's wort found that, of 14 controlled clinical trials, seven reported no adverse reactions, two had no information, and five reported a total of seven mild reactions. Adverse effects reported included stomach upset, fatigue, itching, sleep disturbance, and skin rash. The rate of adverse reactions was always similar to that of the placebo. Additionally, in seven trials comparing St. John's wort with other antidepressants, the adverse reaction rate for St. John's wort was consistently lower than that of the antidepressant drugs with which it was compared.

St. John's wort can make the skin more sensitive to sunlight. Therefore, fair-skinned people should be alert for any rashes or burns following exposure to the sun. Three cases of severe blistering and burns were reported in people taking St. John's wort internally or applying it topically and then being exposed to sunlight. There is a case report of a woman experiencing neuropathy (nerve injury and pain) in sun-exposed skin areas after taking 500 mg of whole St. John's wort for four weeks. Although St. John's wort has photosensitizing properties, the severity of this reaction is not typical for people taking the herb.

People with a history of manic-depressive illness (bipolar disorder) or a less severe condition known as hypomania, should avoid use of St. John's wort as it may trigger a manic episode.

Are there any drug interactions ? Certain medications may interact with St. John's wort. Refer to the drug interactions safety check for a list of those medications