In 2009/2010, the World Health Organization produced updated Medical Eligibility Criteria for
Contraceptive Use (WHOMEC)3 which included evidence-based guidance on contraceptive
use and drug interactions. WHOMEC states that there is intermediate level evidence that the
contraceptive effectiveness of COCs is not affected by co-administration of most broadspectrum
antibiotics, and advises no restriction on use (WHOMEC Category 1) of CHC with
antibiotics. The U.S. Medical Eligibility Criteria for Contraceptive Use (USMEC)4 2010 has also
adopted these recommendations. For the following reasons the CEU supports this statement
and now advises that additional precautions are not required even for short courses of
antibiotics that are not enzyme inducers.