Written by Karen Pilkington, Edzard Ernst and the CAM-Cancer Consortium.
Updated September 21, 2016

St. John's wort (Hypericum perforatum)

Does it work ?

Clinical trials

Very little clinical evidence related to St. John’s wort in cancer has so far emerged. Kacerovsk et al. 22 conducted an uncontrolled, prospective open-label study with 39 patients suffering from actinic keratosis, basal cell carcinoma or Bowen disease. They found promising responses but the nature of the study prevents firm conclusions.

A study on healthy volunteers suggested that hypericum-induced photosensitization might enhance UVB-induced cutaneous damage 23. The relevance of this finding to patients with cancer is, however, as yet unclear.

Proposed anti-inflammatory effects of St John’s wort on the skin were assessed in the treatment of acute skin toxicity in patients undergoing radiotherapy or chemo-radiotherapy for head and neck cancer 37.  A preparation containing St John’s wort and neem oil was used during radiotherapy treatment and follow-up. Beneficial effects were reported but the trial was small (28 patients), a convenience sample was used and there was no control group. Thus, the findings can be considered preliminary at best, particularly as neem oil is also suggested to have anti-inflammatory properties and may have contributed to any effects observed.

Observational studies

A recent update on the data of the VITAL (Vitamins and Lifestyle) study reported a reduced risk for colorectal cancer (CRC) upon consumption of St. John’s wort 24. This observational study, however, cannot establish cause and effect.

Citation Karen Pilkington, Edzard Ernst, CAM-Cancer Consortium. St. John's wort (Hypericum perforatum) [online document]. http://ws.cam-cancer.org/The-Summaries/Herbal-products/St.-John-s-wort-Hypericum-perforatum. September 21, 2016.


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