St. John’s Wort

Parts Used & 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.

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a7_3star Reliable and relatively consistent scientific data showing a substantial health benefit.

a7_2star Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

a7_1star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

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This supplement has been used in connection with the following health conditions:

Used for	Amount	Why
Anxiety	Refer to label instructions	St. John’s wort has been reported in one double-blind study to reduce anxiety.
Anxiety Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.¹ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. St. John’s wort has been reported in one double-blind study to reduce anxiety.² Learn More

Used for	Amount	Why
Depression	600 to 1,200 mg daily of a standardized herbal extract containing of 0.3% hypericin, after consulting with a qualified healthcare professional	St. John’s wort can help with mild to moderate depression—but talk to your doctor first as St. John's wort can interact with certain medications.
Depression 600 to 1,200 mg daily of a standardized herbal extract containing of 0.3% hypericin, after consulting with a qualified healthcare professional Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.³ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. St. John’s wort extracts are among the leading medicines used in Germany by medical doctors for the treatment of mild to moderate depression. Using St. John’s wort extract can significantly relieve the symptoms of depression. People taking St. John’s wort show an improvement in mood and ability to carry out their daily routine. Symptoms such as sadness, hopelessness, worthlessness, exhaustion, and poor sleep also decrease.⁴^{, 5}^{, 6} St. John’s wort extract has been compared to the prescription tricyclic antidepressants imipramine (Tofranil),⁷ ^{, 8} ^{, 9} amitriptyline (Elavil),¹⁰ fluoxetine (Prozac®),¹¹ and maprotiline (Ludiomil).¹² The improvement in symptoms of mild to moderate depression was similar, with notably fewer side effects, in people taking St. John’s wort. In a double-blind trial using standard amounts of fluoxetine (Prozac)—20 mg per day—St. John’s wort extract in the amount of 400 mg twice daily was equally effective at relieving depression in people aged 60–80 years.¹³ Another trial found that 250 mg of St. John’s wort extract two times per day was also as effective as 20 mg of fluoxetine in treating adults with mild to moderate depression.¹⁴ In both trials comparing St. John’s wort to fluoxetine, there were far fewer side effects reported by people taking St. John’s wort. One clinical trial compared a higher amount of the St. John’s wort extract LI 160 (1,800 mg per day) with a higher amount of imipramine (150 mg per day) in more severely depressed people.¹⁵ Again, the improvement was virtually the same for both groups with far fewer side effects for the St. John’s wort group. While this may point to St. John’s wort as a possible treatment for more severe cases of depression, this treatment should only be pursued under the guidance of a healthcare professional. Two well-publicized double-blind studies published in the Journal of the American Medical Association (JAMA) concluded that St. John's wort is not an effective treatment for depression. However, each of these studies had potential flaws. In the first study,¹⁶ 900–1,200 mg of St. John's wort per day was slightly more effective than a placebo, as assessed by the Hamilton Rating Scale for Depression. However, the difference was not statistically significant. Although the remission rate was significantly greater with St. John's wort than with placebo, only 14.3% of the patients who received the herb went into remission, causing the authors of the report to question St. John's wort's efficacy. However, the 4.9% remission rate in the placebo group was far below the placebo response rate seen in other studies of depression. That finding suggests that many of the patients recruited for this study would have been unlikely to respond to any treatment. In the second JAMA study, depressed patients were given one of three treatments: St. John's wort, placebo, or an antidepressant medication with proven efficacy (e.g., sertraline; Zoloft). Although St. John's wort was no more effective than the placebo, by many measures neither was sertraline.¹⁷ The relatively poor outcome with sertraline makes one wonder whether the design of the study, or the criteria used to select participants, may have somehow skewed the results to make St. John's wort appear less effective than it really is. Despite these two negative studies, the bulk of the scientific evidence indicates that St. John's wort is an effective treatment for mild to moderate depression. Recent European trials have successfully treated mild to moderate depression using 500 to 1,050 mg of St. John’s wort per day. As an antidepressant, St. John’s wort should be taken for four to six weeks before judging its effectiveness. Learn More

Used for	Amount	Why
Eczema	Apply a cream containing 5% of an herbal extract standardized to 1.5% hyperforin twice per day	A topical cream containing St. John’s wort was shown in one study to greatly improve the severity of eczema. The herb appears to have anti-inflammatory and antibacterial effects.
Eczema Apply a cream containing 5% of an herbal extract standardized to 1.5% hyperforin twice per day Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.¹⁸ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. In a double-blind trial, people with eczema applied a cream containing an extract of St. John’s wort to the affected areas on one side of the body, and a placebo (the same cream without the St. John’s wort) to the other side. The treatment was administered twice a day for four weeks. The severity of the eczema improved to a significantly greater extent on the side treated with St. John’s wort than on the side treated with placebo.¹⁹ Although the mechanism by which St. John’s wort relieves eczema is not known, it might be due to the anti-inflammatory and antibacterial effects of hyperforin, one of its constituents. The cream used in this study contained 5% of an extract of St. John’s wort (standardized to 1.5% hyperforin). As topical application of St. John’s wort can cause sensitivity to the sun, care should be taken to avoid excessive sun exposure when using this treatment. Learn More

Used for	Amount	Why
Menopause and Depression (Black Cohosh)	Two tablets twice a day for 8 weeks, then one tablet twice a day for 8 weeks, each tablet supplying 1 mg of triterpene glycosides from black cohosh and 0.25 mg of hypericin from St. John's wort	Menopausal and depression symptoms improved in post-menopausal women after they took a combination of black cohosh and St. John's wort.
Menopause and Depression Two tablets twice a day for 8 weeks, then one tablet twice a day for 8 weeks, each tablet supplying 1 mg of triterpene glycosides from black cohosh and 0.25 mg of hypericin from St. John's wort In a double-blind study of postmenopausal women who were experiencing psychological symptoms, a combination of black cohosh and St. John's wort was significantly more effective than a placebo in improving both menopausal symptoms and depression. The product used in this study contained (per tablet) black cohosh standardized to 1 mg of triterpene glycosides and St. John's wort standardized to 0.25 mg of hypericin. The amount taken was two tablets twice a day for eight weeks, followed by one tablet twice a day for eight weeks.²⁰

Used for	Amount	Why
Seasonal Affective Disorder	Consult a qualified healthcare practitioner	St. John’s wort, an herb well known for its antidepressant activity, may improve SAD symptoms.
Seasonal Affective Disorder Consult a qualified healthcare practitioner Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.²¹ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. St. John’s wort, an herb well known for its antidepressant activity,²² has been examined for its effectiveness in treating SAD. In a preliminary trial, patients with seasonal depression were given 900 mg per day of St. John’s wort in addition to either bright light (3,000 lux for two hours) or a dim light (300 lux for two hours) placebo.²³ Both groups had significant improvement in depressive symptoms, but there was no difference between the groups. The authors concluded that St. John’s wort was beneficial with or without bright light therapy, but a placebo effect from the herb cannot be ruled out in this study. Another preliminary study asked 301 SAD patients to report the changes in their symptoms resulting from the use of St. John’s wort at 300 mg three times daily.²⁴ Significant overall improvement was reported by these patients. Some of the subjects used light therapy in addition to St. John’s wort. They reported more improvement in sleep, but overall improvement was not significantly different from those using St. John’s wort alone. Double-blind research is needed to confirm the usefulness of St. John’s wort for treating SAD. Learn More

Used for	Amount	Why
Cold Sores	Refer to label instructions	In traditional herbal medicine, tinctures of various herbs including St. John’s wort have been applied topically to herpes outbreaks in order to promote healing.
Cold Sores Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.²⁵ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. In traditional herbal medicine, tinctures of various herbs, including St. John’s wort, chaparral, goldenseal, myrrh, and echinacea, have been applied topically to herpes outbreaks in order to promote healing. Learn More

Used for	Amount	Why
Ear Infections	Refer to label instructions	Ear drops with mullein, St. John’s wort, and garlic in an oil or glycerin base are traditional remedies used to alleviate symptoms, particularly pain, during acute ear infections.
Ear Infections Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.²⁶ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. Ear drops with mullein, St. John’s wort, and garlic in an oil or glycerin base are traditional remedies used to alleviate symptoms, particularly pain, during acute ear infections. No clinical trials have investigated the effects of these herbs in people with ear infections. Moreover, oil preparations may obscure a physician’s view of the ear drum and should only be used with a healthcare professional’s directions. Learn More

Used for	Amount	Why
HIV and AIDS Support	Refer to label instructions	A preliminary trial found that people infected with HIV who took hypericin, a constituent from St. John’s wort, had some improvements in CD4+ cell counts.
HIV and AIDS Support Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.²⁷ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. A constituent from St. John’s wort known as hypericin has been extensively studied as a potential way to kill HIV. A preliminary trial found that people infected with HIV who took 1 mg of hypericin per day by mouth had some improvements in CD4+ cell counts, particularly if they had not previously used AZT.²⁸ A small number of people developed signs of mild liver damage in this study. Another much longer preliminary trial used injectable extracts of St. John’s wort twice a week combined with three tablets of a standardized extract of St. John’s wort taken three times per day by mouth. This study found not only improvements in CD4+ counts but only 2 of 16 participants developed opportunistic infections.²⁹ No liver damage or any other side effects were noted in this trial. In a later study, much higher amounts of injectable or oral hypericin (0.25 mg/kg body weight or higher) led to serious side effects, primarily extreme sensitivity to sunlight.³⁰ At this point, it is unlikely that isolated hypericin or supplements of St. John’s wort extract supplying very high levels of hypericin can safely be used by people with HIV infection, particularly given St. John’s wort’s many drug interactions. Learn More

Used for	Amount	Why
Infection	Refer to label instructions	St. John’s wort is an herb that directly attack microbes.
Infection Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.³¹ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. Herbs that directly attack microbes include the following: chaparral, eucalyptus, garlic, green tea, lemon balm (antiviral), lomatium, myrrh, olive leaf, onion, oregano, pau d’arco (antifungal), rosemary, sage, sandalwood, St. John’s wort, tea tree oil, thyme, and usnea. Learn More

Used for	Amount	Why
Menopause	Refer to label instructions	Supplementing with St. John’s wort may improve psychological symptoms, including sexual well-being, in menopausal women.
Menopause Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.³² Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. In a double-blind study of postmenopausal women who were experiencing psychological symptoms, a combination of black cohosh and St. John's wort was significantly more effective than a placebo in improving both menopausal symptoms and depression. The product used in this study contained (per tablet) black cohosh standardized to 1 mg of triterpene glycosides and St. John's wort standardized to 0.25 mg of hypericin. The amount taken was two tablets twice a day for eight weeks, followed by one tablet twice a day for eight weeks.³³ Preliminary evidence suggests that supplementation with St. John’s wort extract (300 mg three times daily for 12 weeks) may improve psychological symptoms, including sexual well-being, in menopausal women.³⁴ ³⁵ Learn More

Used for	Amount	Why
Ulcerative Colitis	Refer to label instructions	St. John’s wort, administered as an enema, may be beneficial for people with ulcerative colitis.
Ulcerative Colitis Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.³⁶ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. Enemas of oil of St. John’s wort may be beneficial for ulcerative colitis.³⁷ Consult with a doctor before using St. John’s wort oil enemas. Learn More

Used for	Amount	Why
Wound Healing	Refer to label instructions	Topically applied St. John’s wort can be used to speed wound healing.
Wound Healing Caution: It is likely that there are many drug interactions with St. John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the market.³⁸ Therefore, it could potentially cause a number of drug interactions that have not yet been reported. People taking any medication should consult with a doctor or pharmacist before taking St. John's wort. Traditional herbalists sometimes recommend the topical use of herbs such as St. John’s wort, calendula, chamomile, and plantain, either alone or in combination, to speed wound healing. Clinical trial in humans have not yet validated this traditional practice. Learn More

Traditional Use (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.

Also indexed as:

botanicals,
herbal dietary supplements,
herbal medicine,
herbal remedies,
herbal therapy,
herbalism,
Hypericum perforatum,
klamath weed,
plant Medicine,
st johns wort,
St. John's wort

About this treatment

Common names:

Hypericum, Klamath Weed

Botanical names:

Hypericum perforatum

How It Works

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 to Use It

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.

Interactions

Last Review: 05-11-2011

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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2011.

© 1995-2011 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

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