St. John's wort

What Is It?
Health Benefits
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects
Evidence Based Rating Scale

What Is It?

St. John's wort (Hypericum perforatum), a common shrub-like perennial, bears bright yellow flowers that contain numerous therapeutic substances when dried. Europeans have used the Herb for centuries to calm jangled nerves and heal wounds, among other ills. And so it's not surprising that North Americans have recently embraced its use as a treatment for depression and conditions associated with it. Not only is St. John's wort effective and relatively free of side effects, it also costs under $20 for a month's supply, about 75% less than the most popular Antidepressant drugs. In Germany, where doctors routinely prescribe herbal remedies, St. John's wort is the most common form of antidepressant—more widely used than the drugs Prozac or Zoloft because it has far fewer side effects.  

Health Benefits

Although St. John's wort has been the focus of a number of well-regarded studies, researchers still don't know exactly how the herb works. A pigment called hypericin has long been identified as a key medicinal ingredient, although other compounds are now also believed to contribute to the herb's therapeutic effects. In general, St. John's wort appears to boost levels of the brain chemical Serotonin, which affects the emotions. The National Institutes of Health (NIH), in Washington D.C., have sponsored numerous studies on the efficacy of St. John’s Wort for a variety of psychological conditions. Because of its widespread use among the public, research to determine St. John’s Wort interactions with other commonly prescribed drugs is another important area of investigation. 

A number of other uses for St. John's wort have been proposed as well, many of them related to the herb's anti-depressant actions. The herb is even being investigated as a treatment for alcoholism, panic attacks, and general anxiety. 

Specifically, St. John's wort may help to: 

• Relieve mild to moderate depression. Germany’s Commission E approved St. John’s wort for the treatment of depression in 1998. (1) Then in 2000, a team of researchers from the Center for Complementary Medicine Research in Munich, Germany conducted a Cochrane Database Review of 27 studies of St. John's wort that included a total of 2,291 study participants. They concluded that the herb works better than Placebo in the treatment of mild to moderate depression (2). In an update to that review, the same researchers concluded that taking St. John’s wort extracts seems to improve mood and to decrease anxiety and physical symptoms, as well as to decrease insomnia related to mild to severe depression. The review also upheld results from previous studies that showed taking St. John’s wort is as effective in treating depression as conventional antidepressants and results in fewer side effects (3-11). While initial studies indicated that response rates to St. John’s wort were higher during short-term use than during long-term use, a 2009 open, multi-center study also showed potential benefits of long-term use. In the study, 440 out-patients suffering from mild to moderate depression were treated with 500 mg of a specific St. John’s wort extract (Ze 117) daily for one year. Results indicated improvements in depression scores with fewer than 6% of patients reporting side effects related to the treatment. St. John’s wort, in this formulation, appeared to be a safe and efficacious treatment for mild to moderate depression over long periods of time; it was especially useful in preventing relapse. (12) 

Some evidence has shown the herb may also aid in treating depressive elements of seasonal affective disorder (also known as SAD or "wintertime blues"), a type of depression linked to the shortage of daylight in the fall and winter (13). Other studies have shown the depression and tension often associated with this disorder, as well as with anxiety, stress and chronic pain, may lessen with the use of St. John’s wort. In a 1999 study of 168 patients, taking St. John’s wort for eight weeks improved symptoms of anxiety, decreased libido, and sleep disturbances associated with SAD. Treatment was beneficial when used alone or in combination with light therapy. (14)  

• Control certain symptoms of Pre-Menstrual Syndrome (PMS). Many women experience depression as a primary symptom of PMS (premenstrual syndrome). In such cases, St. John's wort may be worth a try. The herb can be used regularly for this purpose, but it may take one or two menstrual cycles for the active ingredients to reach therapeutic levels in the body and to lessen emotional upset. European women have been turning to this herbal PMS cure for years. Preliminary evidence indicates that taking a St. John’s wort extract standardized to 900 mcg hypericin for two complete menstrual cycles seems to improve the severity of symptoms of PMS by up to 50% in some women. (15) A 2004 trial of 125 normally menstruating women taking 600 mg of St. John’s wort (standardized to contain 1,800 mcg of hypericin) or placebo over the course of two years found a trend for the herb to be more effective than placebo in treating symptoms of PMS. However, the results were not statistically significant. (16) A 2009 review of herbs, vitamins and minerals used for the treatment of PMS found St. John’s wort was one of ten alternative treatments with randomized controlled trials that offered some evidence of efficacy. The data showed St. John’s wort to be more effective than placebo. (17) A 2010 randomized, double-blind, placebo-controlled crossover study of 36 women found that treatment with 900 mg of St. John’s wort (standardized to 1,800 mcg hypericin) was more effective than placebo in treating physical and behavioral symptoms. However, no significant effects on mood, pain-related symptoms, anxiety, depression, aggression or impulsivity were found in either group. (18) More research is needed. 

• Treat some symptoms of Menopause Some women, particularly those with a prior history of depression, experience increased levels of depression as they approach and go through menopause. When combined with a specific black cohosh extract (Remifemin), St. John’s wort has been shown to significantly reduce these depressive symptoms when associated with menopause. (19) Further evidence indicates that a different specific formulation of St. John’s wort and black cohosh extract (Gynoplus, Jin-Yang Pharm) significantly reduced menopausal symptoms compared to placebo. (20) Using St. John’s wort alone also has been shown to improve hot flashes related to menopause. A 2010 randomized controlled trial of 100 women showed that taking St. John’s wort for eight weeks reduced the frequency, duration and severity of hot flashes compared to placebo. (21)  

• Ward off infections. St. John's wort has been shown to have antibacterial and antiviral properties. It's particularly effective when applied topically (in the form of an ointment) for the treatment of burns, cuts, scrapes, and minor skin irritations (22, 23). Some preliminary laboratory studies indicate that St. John's wort might also be useful against herpes simplex, influenza, and the Epstein-Barr virus (the cause of mononucleosis). (24) Clinical trials are still needed to confirm these findings, however. 

• Relieve hemorrhoids. St. John's wort cream or ointment may help to soothe the pain of hemorrhoids. The anti-inflammatory, antibacterial and antiviral properties of St. John’s wort may help to relieve the burning and itching, as well as to shrink the inflamed and swollen tissue. While some alternative sources indicate this use for St. John’s wort, scientific studies are lacking. (25, 26) 

• Treat nerve injuries. In its homeopathic form, St. John’s wort is sold over the counter as medicated lactose pellets under its Latin name, Hypericum perforatum. The primary indication for its use according to homeopathic texts is treatment of injuries to tissues that are rich with nerves, e.g. the fingers, toes, tailbone, and area around the mouth, where it is reputed to help relieve pain related to nerve injury. (27, 28)  


  • Tincture
  • tablet
  • softgel
  • ointment
  • cream
  • capsule
  • homeopathic lactose pellets 

Dosage Information

Special tip:

Although most clinical studies have been done using an Extract standardized for hypericin, there seems to be some doubt as to what aspect of the herb is truly responsible for its clinical efficacy. Research findings indicate that a substance called hyperforin may have even more potent mood-enhancing properties than hypericin (29). For this reason, when treating depression, look for an extract standardized to contain 0.3% hypericin and 3.0% hyperforin.

• For depression, PMS, and the majority of other ailments mentioned: Take 900 mg a day--either a 300 mg pill three times a day or a 450 mg pill twice a day. To avoid missing doses, you can also simplify the regimen by taking two 300 mg capsules in the morning and one in the evening (or vice versa). If using a tincture, follow the instructions on the bottle for dosage equivalence.  

• For skin infections and hemorrhoids: Apply St. John's wort ointment three or four times a day. Use an ointment when treating hemorrhoids, applying it several times a day and, when possible, directly after bowel movements. 

• For injuries with sharp shooting pains: Dissolve 3-5 pellets of homeopathic Hypericum perforatum 30c under the tongue three times a day or as needed. 

Be sure to check out our Dosage Recommendations Chart for St. John's Wort, which lists therapeutic dosages for specific ailments at a glance.  

Guidelines for Use

• St. John's wort herb takes some time to build up in the blood, so allow at least four weeks for it to take effect. It can be used long term as needed.

• Take St. John's wort with meals to reduce the risk of stomach irritation.

• No foods are off limits for those taking St. John's wort, not even aged cheese and red wine, which are not recommended for those on MAO inhibitors.

• To prevent the risk of adverse reactions, avoid making home preparations of the plant. Stick to standardized supplements available over the counter.  

General Interaction

• St. John's wort is now known to affect the way the liver metabolizes many drugs. This can result in a loss of effectiveness of the other drugs for the other problems or illnesses for which you are being treated. If you are already taking prescribed medication, don't start taking St. John's Wort without consulting your pharmacist or doctor about possible interactions.

• Although rare, serious adverse reactions have been reported from the combination of a conventional antidepressant, such as Prozac and Zoloft, with St. John's wort. Don't start taking St. John's wort without consulting a doctor.

• Certain medications, such as tetracycline and fluoroquinolone antibiotics, can increase the skin's sensitivity to the sun, so avoid taking St. John's wort, which can also have this effect, at the same time. Consult a doctor for more information.

• Because St. John's wort and oral contraceptives are metabolized in the liver by the same mechanism; the effectiveness of the hormonal contraceptives may be compromised. Consult a doctor (30-32).

• Studies have shown significant interaction between St. John's wort and indinavir, a protease inhibitor drug used to treat HIV infection and cyclosporine used to suppress the immune response in patients who have received organ transplants. (33). It showed that taking St. John's wort at the same time as indinavir greatly reduced the effectiveness of indinavir. St. John's wort may also affect other protease inhibitors--such as saquinavir--in a similar manner. Caution is advised.

• Because the herb's exact mechanism of action is still unclear, it's probably not wise to combine it with MAO inhibitors, medications prescribed for depression and Parkinson's disease.

For information on interactions with specific drugs, see our WholeHealthMD Drug/Nutrient Interactions Chart.  

Possible Side Effects

• Side effects are uncommon but can include fatigue, dry mouth, dizziness, constipation, and upset stomach.

• Some people experience increased sun sensitivity when taking St. John's wort, especially if they are exposed to the sun for long periods of time (34). Skin reactions in AIDS patients taking high doses of St. John's wort were so severe in one trial that many stopped participating. So while sun sensitivity is not a problem for most people at commonly recommended doses, be sure to contact a doctor if an unexpected rash or excessive burn develops after being in the sun (35,36). 


• Anyone taking prescription drugs should check with a physician before taking St. John’s wort. Many commonly prescribed prescription medications are metabolized by the same mechanism as St. John’s wort; potential interactions could alter the effect of conventional drugs and lead to serious adverse reactions. (37-40).

• Never stop taking prescription antidepressants (or even lower the dosage) without checking with a doctor first.

• Serious allergic reactions to any food, herb or medication are always possible. Fortunately, such allergies to St. John's wort are extremely rare. However, if hives or wheezing develop after taking the herb, get immediate medical help.

• Though no adverse effects have been reported in pregnant or lactating women using the herb, there have been few studies on this group, so caution is advised.

• Before surgery, if taking herbal supplements, discuss all treatments with all of the clinicians who may be involved in your care. St. John’s wort may alter the metabolism of many drugs commonly prescribed in the peri-operative period (41, 42).

• During cancer treatment, if taking herbal supplements, discuss all treatments with the clinicians involved in providing care.  Preliminary studies show that St. John’s wort may have a negative effect on irinotecan as a treatment for cancer (43).  


1. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin, TX: American Botanical Council; 1998.
2. Linde, K. and Mulrow, C. D. St John's wort for depression. Cochrane Database Syst Rev. 2000; (2):CD000448.
3. Linde K, Berner MM, Kriston L. St. John’s wort for major depression. Cochrane Database Syst Rev. 2008 Oct 8;(4):CD000448. Comment in: Evid Based Met Health. 2009 Aug;12(3):78.
4. Kim HL, Streltzer J, Goebert D. St. John's wort for depression: A meta analysis of well-defined clinical trials. J Nerv Ment Dis 1999;187:532-9.|
5. Linde K, Ramirez G, Mulrow CD, et al. St. John's wort for depression: an overview and meta-analysis of randomized clinical trials. BMJ 1996;313:253-8.
6. Philipp M, Kohnen R, Hiller KO. Hypericum extract versus imipramine or placebo in patients with moderate depression: randomized multicentre study of treatment for eight weeks. BMJ 1999;319:1534-9.
7. Woelk H. Comparison of St. John’s wort and imipramine for treating depression: randomized controlled trial. BMJ 2000;321:536-9.
8. Harrer G, Schmidt U, Kuhn U, Biller A. Comparison of equivalence between the St. John's wort extract LoHyp-57 and fluoxetine. Arzneimittelforschung 1999;49:289-96.
9. Schrader E. Equivalence of St. John's wort extract (Ze 117) and fluoxetine: a randomized, controlled study in mild-moderate depression. Int Clin Psychopharmacol 2000;15:61-8.
10. Brenner R, Azbel V, Madhusoodanan S, et al. Comparison of an extract of Hypericum (LI 160) and sertraline in the treatment of depression: A double-blind, randomized pilot study. Clin Ther. 2000;22:411-9.
11. Szegedi A, Kohnen R, Dienel A, Kieser M. Acute treatment of moderate to severe depression with hypericum extract WS 5570 (St. John’s wort): randomized controlled double-blind non-inferiority trial versus paroxetine. BMJ 2005;330:503.
12. Brattström A. Long-term effects of St. John’s wort (Hypericum perforatum) treatment: a 1-year safety study in mild to moderate depression. Phytomedicine. 2009 Apr;16(4):277-83.
13. Kasper, S. Treatment of seasonal affective disorder (SAD) with hypericum extract. Pharmacopsychiatry. 1997 Sep; 30 Suppl 2:89-93.
14. Wheatley D. Hypericum in seasonal affective disorder (SAD). Curr Med Res Opin. 1999;15:33-7.
15. Stevinson C, Ernst E. A pilot study of Hypericum perforatum for the treatment of premenstrual syndrome. BJOG 2000;107:870-6.
16. Hicks SM, Walkder AF, Gallagher J, et al. The significance of “nonsignificance” in randomized controlled studies: a discussion inspired by a double-blinded study on St. John’s wort (Hypericum perforatum L.) for premenstrual symptoms. J Altern Complement Med. 2004 Dec;10(6):925-32.
17. Whelan AM, Jurgens TM, Naylor H. Herbs, vitamins and minerals in the treatment of premenstrual syndrome: a systematic review. Can J Clin Pharmacol. 2009 Fall;16(3):e407-29.
18. Canning S, Waterman M, Orsi N, et al. The efficacy of Hypericum perforatum (St. John’s wort) for the treatment of premenstrual syndrome: a randomized, double-blind, placebo-controlled trial. CNS Drugs. 2010 Mar 1;24(3):207-25.
19. Uebelhack R, Blohmer JU, Graubaum HJ, et al. Black cohosh and St. John’s wort for climacteric complaints: a randomized trial. Obstet Gynecol. 2006 Feb;107(2 Pt 1):247-55.
20. Chung DJ, Kim HY, Park KH, et al. Black cohosh and St. John’s wort (GYNO-Plus) for climacteric symptoms. Yonsei Med J. 2007;48:289-94.
21. Abdali K, Khajehei M, Tabatabaee HR. Effect of St. John’s wort on severity, frequency, and duration of hot flashes in premenopausal, perimenopausal and postmenopausal women: a randomized, double-blind, placebo-controlled study. Menopause. 2010 Mar;17(2):326-31.
22. Schempp, C. M.; Hezel,S., and Simon, J. C. Topical treatment of atopic dermatitis with Hypericum cream. A randomised, placebo-controlled, double-blind half-side comparison study].Hautarzt. 2003 Mar; 54(3):248-53.
23. Schempp, C. M.; Winghofer, B.; Ludtke, R.; Simon-Haarhaus, B.; Schopf, E., and Simon, J. C. Topical application of St John's wort (Hypericum perforatum L.) and of its metabolite hyperforin inhibits the allostimulatory capacity of epidermal cells. Br J Dermatol. 2000 May; 142(5):979-84.
24. Schempp C,

Date Published: 04/19/2005
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