Depression Home > St. John's Wort Side Effects

Some of the possible side effects of St. John's wort include diarrhea, insomnia, and headaches. Although these reactions are merely bothersome, more serious side effects can also occur while using the supplement. Potentially serious problems include heart palpitations, hallucinations, or signs of an allergic reaction. If you experience any of these side effects, report them to your healthcare provider immediately.

Does St. John's Wort Cause Side Effects?

As with any medication or supplement, St. John's wort (Hypericum perforatum) can cause side effects. Many people assume that natural products such as St. John's wort are always free of side effects. However, this is simply not the case. Any herb that has medicinal properties may also have side effects.
(This article covers many, but not all, of the possible side effects of St. John's wort. Your healthcare provider can discuss a more complete list with you.)

Bothersome Side Effects of St. John's Wort

Possible bothersome (although not usually serious) side effects seen with this supplement may include:

Side Effects to Report

Some St. John's wort side effects, while occurring infrequently, are potentially serious and should be reported to your healthcare provider. These include but are not limited to:
  • Anxiety, agitation, or panic attacks
  • Hostility or aggressiveness
  • Engaging in unusual or dangerous activities
  • Restlessness or an inability to sit still
  • Extreme elation or feelings of happiness that may switch back and forth with a depressed or sad mood
  • Other unusual changes in behavior
  • Hallucinations
  • A fast heart rate (tachycardia)
  • High blood pressure (hypertension)
  • Feelings of a rapidly or forcefully beating heart (known as heart palpitations)
  • Severe sun sensitivity
  • Signs of an allergic reaction, such as:
    • Rash
    • Hives
    • Itching
    • Swelling of the mouth or throat
    • Wheezing
    • Difficulty breathing.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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