St. John's wort (Hypericum perforatum) is a five-petal yellow flower that is often taken for a number of medicinal uses. While there are several purported uses of St. John’s wort, there is limited evidence of its effectiveness for most conditions.
St. John's wort may be good for:
- Depression
- There is inconsistent evidence for its effectiveness for this use
- Some studies have found standardized extracts of St. John's wort were more effective than placebo and comparable in efficacy to standard antidepressants for the treatment of mild to moderate depression at 12 weeks
- Somatoform disorders (psychosomatic disorders)
- In limited studies, St. John's wort has shown some evidence of efficacy in the treatment of somatoform disorders but the results are limited by short follow-up
- Menopausal symptoms
- There is some evidence suggesting St. John's wort is effective in treating menopause-related hot flashes, but all the trials included small sample size and were deficient in other areas
There is no evidence to support the use of St. John’s wort for the following conditions:
- Attention deficit hyperactivity disorder (ADHD)
- One trial of children and adolescents with ADHD showed no improvement in attention or hyperactivity symptoms with St. John's compared with placebo
- Human immunodeficiency virus (HIV) infection
- In a phase I trial of HIV-infected patients with CD4 counts less than 350 cells/mm3, over half of subjects stopped the trial early due to moderate or severe phototoxicity, there was no demonstrable antiretroviral activity at the doses tested, and therapy was considered too toxic
- Smoking cessation
- In trials of St. John's wort for smoking cessation, no benefit of treatment was found compared with placebo
- Irritable bowel syndrome (IBS)
- In one trial of the use of St. John's wort for IBS, it was found to be less effective than placebo as measured by self-reported bowel symptom score
What Are Side Effects of St. John’s Wort?
Side effects of St. John’s wort include:
- Gastrointestinal symptoms
- Dizziness
- Confusion
- Tiredness/sedation
- Skin sensitivity to sunlight (photosensitivity)
- Dry mouth
- Urinary frequency
- Inability to achieve orgasm (anorgasmia)
- Swelling
- In addition, St. John's wort is not recommended for use during pregnancy or while breastfeeding since high-quality data demonstrating safety are lacking.
What Are Drug Interactions with St. John’s Wort?
St. John's wort interacts with many medications and it is important to talk to your doctor before using St. John’s wort because of the potential for interactions with prescription drugs, over-the-counter (OTC) medicines, and nonprescription herbs and supplements.
Some drugs that may interact with St. John’s wort include:
- Warfarin
- HIV antiretrovirals
- Antifungals
- Topical beta blockers for glaucoma
- Immunosuppressive agents for prevention of graft rejection
- Narcotics
- Digoxin
- Hormonal contraceptives
- Antidepressants (to avoid the potential for the serotonin syndrome)
Because of the various potential drug interactions with St. John's wort, it should be discontinued at least five days prior to a planned surgical procedure.
Another concern about the use of St. John’s wort is the variability in the quality and contents of available supplements. For patients who choose to use it, look for products that meet specific quality criteria according to independent laboratory testing.
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