July 30, 2016

St. John's Wort

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How does St. John's Wort work?

For a long time, investigators thought a chemical in St. John's wort called hypericin was responsible for its effects against depression. More recent information suggests another chemical, hyperforin, as well as adhyperforin, and several other similar chemicals may play a larger role in depression. Hyperforin and adhyperforin act on chemical messengers in the nervous system that regulate mood.

Are there safety concerns?

St. John's wort is LIKELY SAFE when taken by mouth for up to 12 weeks. Some evidence suggests it can be used safely for over one year. It can cause some side effects such as trouble sleeping, vivid dreams, restlessness, anxiety, irritability, stomach upset, fatigue, dry mouth, dizziness, headache, skin rash, diarrhea, and tingling. Take St. John's wort in the morning or lower the dose if it seems to be causing sleep problems.

St. John's wort is POSSIBLY UNSAFE when taken by mouth in large doses. When taken by mouth in large doses, it might cause severe reactions to sun exposure. Wear sun block outside, especially if you are light-skinned.

St. John's wort interacts with many drugs (see the section below). Let your healthcare provider know if you want to take St. John's wort. Your healthcare provider will want to review your medications to see if there could be any problems.

There isn't enough reliable information available to know if St. John's wort is safe when it is applied to the skin. St. John's wort might cause severe reactions to sun exposure.

Special Precautions & Warnings:

Pregnancy and breast-feeding: St. John's wort is POSSIBLY UNSAFE when taken by mouth during pregnancy. There is some evidence that it can cause birth defects in unborn rats. No one yet knows whether it has the same effect in unborn humans. Nursing infants of mothers who take St. John's wort can experience colic, drowsiness, and listlessness. Until more is known, do not use St. John's wort if you are pregnant or breast-feeding.

Children: St. John's work is POSSIBLY SAFE when taken by mouth for up to 8 weeks in children 6-17 years-old.

Alzheimer's disease: There is concern that St. John's wort might contribute to dementia in people with Alzheimer's disease.

Anesthesia: Use of anesthesia in people who have used St. John's wort for 6 months may lead to serious heart complications during surgery. Stop using St. John's wort at least 2 weeks before a scheduled surgery.

Attention deficit-hyperactivity disorder (ADHD): There is some concern that St. John's wort might worsen symptoms of ADHD, especially in people taking the medication methylphenidate for ADHD. Until more is known, don't use St. John's wort if you are taking methylphenidate.

Bipolar disorder: People with bipolar disorder cycle between depression and mania, a state marked by excessive physical activity and impulsive behavior. St. John's wort can bring on mania in these individuals and can also speed up the cycling between depression and mania.

Depression: In people with major depression, St. John's wort might bring on mania, a state marked by excessive physical activity and impulsive behavior.

Infertility: There are some concerns that St. John's wort might interfere with conceiving a child. If you are trying to conceive, don't use St. John's wort, especially if you have known fertility problems.

Schizophrenia: St. John's wort might bring on psychosis in some people with schizophrenia.

Surgery: St. John's wort might affect serotonin levels in the brain and as a result interfere with surgical procedures. Stop using St. John's wort at least two weeks before a scheduled surgery.


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