People with fair skin undergoing UV treatment should use high doses of St John’s wort with caution. Suspend use of St John’s wort 2 weeks prior to major surgery.
A study conducted in an experimental animal model found no adverse effects on offspring with maternal use; however, safe doses in pregnant women have not been determined. In practice, it is not used in pregnancy.
St John’s appears to be relatively safe in lactation. A study of breast feeding mothers indicated that low levels of hyperforin are excreted into breast milk; however, infant exposure is comparable to levels reported in most studies assessing antidepressants or neuroleptics and no side-effects were seen in the mothers or infants. The doses used were 300 mg of St John’s wort (LI 160, three times daily).
Practice Points / Patient Counselling
• St John’s wort contains numerous constituents with pharmacological activity, including antidepressant, analgesic, anti-inflammatory, antispasmodic, anxiolytic, antineoplastic, antiviral and bactericidal activities.
• Numerous clinical studies support the use of St John’s wort as an effective treatment for mild to moderate depression. The most commonly studied extract is LI 160 although others have also been tested (e.g. WS 5573 (standardised to hyperforin), ZE 117 (a low concentration hyperforin preparation), WS 550 and STW3-V1). Clinical effects are comparable to tricyclic antidepressants and SSRIs.
• In regards to safety, St John’s wort is better tolerated than standard antidepressants; however, it still needs to be prescribed judiciously to avoid interactions.
• Low-hyperforin-containing St John’s wort extracts do not have the same interaction potential as standard St John’s wort extracts and may present a safer option for some individuals.
• Efficacy in severe depression has not been established, with mixed results reported so far.
• Preliminary human studies have suggested a possible role in PMS, SAD, OCD and in menopausal and premenopausal women with psychological and psychosomatic symptoms.