Primum non nocere: thoughts on the need to develop an 'adverse events' register for complementary and alternative therapies.

Building a body of knowledge to support the efficacy and practice of complementary and alternative therapies is an imperative that should be fully embraced by all those involved. Additional endeavours to monitor adverse events related to complementary and alternative therapies should also be pursued. The history and extent of medical iatrogenesis is briefly outlined, as is the literature on adverse events related to complementary and alternative therapies. Allopathic medicine is slowly realising the negative impact of iatrogenesis and is starting to develop systems to monitor such events in order to reduce or eliminate their existence. It is suggested that a similar development is needed in complementary and alternative therapies, so that it can be ensured that, at a minimum, primum non nocere, the therapy should firstly do no harm.