St John’s Wort and certain antidepressants, can cause ‘serotonin syndrome’ a serious condition marked by confusion, uncoordination, and cardiovascular irregularities.
St John’s Wort and sunlight can cause photosensitivity, especially if combined with other photosensitizing drugs like certain antibiotics.
In addition, fatigue and gastrointestinal upset occur in some people. Avoid standardized St. John’s Wort if you use tanning beds or take drugs that cause photosensitivity (You might get burned!).
Preliminary research suggests high doses of St. John’s Wort may also increase the risk of sun-induced cataracts.