Overview Effects of St. John's Wort on the Oral Contraceptive Hormone Levonorgestrel Status: Completed Trial end date: 2008-05-01 Target enrollment: Participant gender: Summary This study will determine the effects of St. John's wort, a common herbal remedy, on metabolism of the female contraceptive hormone levonorgestrel. Phase: Phase 4 Details Lead Sponsor: University of UtahCollaborator: National Center for Complementary and Integrative Health (NCCIH)Treatments: Levonorgestrel