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What is St. John's wort?


St. John's wort is an herbal remedy that comes from the plant, Hypericum perforatu. Many people believe that St. John's wort can improve symptoms of anxiety and mild depression. There are at least ten active compounds in St. John's wort and it's not yet clear which of them are responsible for the herb's activity.

Some research studies showed that St. John's wort is equal or less effective to the older antidepressants like amitriptyline (Elavil®) and imipramine (Tofranil®). Recent studies have also reported that St. John's wort reduces symptoms of mild to moderate depression just as well as newer antidepressants such as fluoxetine (Prozac® ) and sertraline (Zoloft®). Longer term studies are needed to confirm and validate these effects. It may take up to eight weeks to feel the full effects of this herb. If you don't notice improvement after four to six weeks, let your doctor know.

St. John's wort is available in drops, extracts, capsules, tablets, and powders. In most research for depression, people took an extract containing 0.3% hypericin at a dose of 300mg three times a day.

Most common St. John's wort side effects

The most commonly reported side effects of St. John's wort are nausea and sun sensitivity. Fair-skinned people should use a sunscreen with a SPF of 15 or higher while spending long periods in the sun. Less common side effects are dry mouth, itching and rash, fatigue, and restlessness. Pregnant women should not take St. John's wort.

Interactions with St. John's wort

St. John's wort is generally considered a safe treatment but there are several known interactions with various drugs. Researchers at the National Institutes of Health reported that St. John's wort can significantly reduce the effectiveness of the protease inhibitor indinavir (Crixivan®) which is often prescribed for patients with human immunodeficiency virus (HIV) infection. When taken with St. John's wort, levels of Crixivan® in the blood dropped dramatically. This drug interaction could allow a patient's virus infection to worsen or increase the odds that the virus will develop resistance to the drug.

Another recent study has found that St. John's wort can interfere with cyclosporine, a drug used to keep transplant patients from rejecting their new organs. Other drugs that may be similarly affected include other antiviral medicines, certain heart medicines, birth control pills, seizure medicines, antianxiety drugs, anticoagulant drugs such as warfarin (Coumadin®), and anticancer drugs. The Food and Drug Administration (FDA) recommends that people who take any of these drugs consult their doctor before using St. John's wort.

In addition, don't combine St. John's wort with the prescription medicines piroxicam (Feldene®) or tetracycline. These combinations can make the skin very sensitive to sunlight and increase the chance of severe sunburn. It's also wise to avoid taking St. John's wort along with other types of drugs and supplements as well, including prescription antidepressants, bromocriptine (Parlodel®), pseudoephedrine (Sudafed®), yohimbine, or ma huang. In rare cases, these combinations may lead to headache, sweating, dizziness, muscle spasms, and increased blood pressure.

This list is not all-inclusive, so always be sure to talk to your doctor before taking herbal or alternative medicines.

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Answers to questions regarding information about medications or health conditions are not for diagnostic or treatment purposes and are not conclusive as to the presence or absence of any health condition. Consult your physician for diagnosis and treatment of your medical condition. The information provided is not a substitute for medical advice. Advances in medicine may cause this information to become outdated, invalid or subject to debate. Professional opinions and interpretations of the scientific literature may vary. Walgreens' terms of use and general warranty disclaimer apply to all services provided. If you are in need of immediate medical attention, contact your physician, poison control center or emergency medical professional. If you need to speak with a pharmacist for non-emergency matters, contact your local Walgreens pharmacist or call a pharmacist toll-free at 1 (877) 250-5823.

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