St John's wort and menopause (perimenopause)

• Black cohosh (cimicifuga racemosa) is a herbal medicine that has traditionally been used to treat a variety of conditions including rheumatism, rheumatoid arthritis, intercostal myalgia, sciatica, chorea, tinnitus, dysmenorrhoea, and uterine colic
  • currently black cohosh is mainly used to treat menopausal symptoms and it may become more widely used as women seek an alternative to hormone replacement therapy
    • there is evidence concerning the use of a fixed combination of black cohosh and St John's wort in reducing perimenopausal (climacteric) and depressive symptoms (1)
    • however the long term safety of black cohosh is not clear
• adverse effects of black cohosh include gastrointestinal irritation, headache, dizziness and vomiting
• hepatotoxicity with black cohosh - there have been 10 reports of suspected adverse reactions associated with black cohosh, 7 of which have been reports of hepatotoxicity
  • mechanism for hepatotoxicity with black cohosh is not known. However, an immunological response has been suggested

NICE state (3):

• there is some evidence that isoflavones or black cohosh may relieve vasomotor symptoms
  • however
    • multiple preparations are available and their safety is uncertain
    • different preparations may vary
    • interactions with other medicines have been reported
• advise people with a personal history of, or at high risk of, breast cancer that, although there is some evidence that St John's wort may help relieve vasomotor symptoms associated with menopause, there is uncertainty about:
  • appropriate dosage
  • persistence of effect
  • variation in the nature and potency of preparations
  • potential serious interactions with other medicines (including tamoxifen, anticoagulants and anticonvulsants)

Reference:

1. Uebelhack R et al. Black cohosh and St John's wort for climacteric complaints: a randomized trial. Obstet Gynecol 2006;107:247-55.
2. Current Problems in Pharmacovigilance (2004); 30:1-12.
3. NICE (November 2024). Menopause: diagnosis and management