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 dose. 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.
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.
Infertility: There are some concerns that St John’s wort might interfere with conceiving a child. If you are trying to conceive, do not use St John’s wort, especially if you have known fertility problems.
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, do not 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.
Major depression: In people with major depression, St John’s wort might bring on mania, a state marked by excessive physical activity and impulsive behavior.
Schizophrenia: St John’s wort might bring on psychosis in some people with schizophrenia.
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 six months may lead to serious heart complications during surgery. Stop using St John’s wort at least two weeks prior to a scheduled surgery.
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 prior to a scheduled surgery.