Does St. John's Wort interfere with the antiandrogenic effect of oral contraceptive pills?

Background: St. John's wort (SJW), a commonly used herbal remedy, has been shown to compromise the efficacy of drugs, including oral contraceptive pills (OCPs), by inducing cytochrome P-450. We investigated whether the simultaneous use of SJW with OCPs resulted in elevated serum androgen levels with implications of impaired OCP treatment of hirsutism and acne. Materials and Methods: Fifteen healthy women were treated with the low-dose OC Loestrin 1/20 (TM) for 2 months and then additionally with SJW for 2 months. Androgen and sex hormone-binding globulin (SHBG) levels were measured in serum by immunoassay methods; free testosterone (fT) was calculated. Results were analyzed using the Wilcoxon signed-rank test. Results: There were no statistically significant differences in androgen levels after the addition of SJW in women using Loestrin 1/20 (TM). However, there were decreases in total testosterone and fT levels (10.7% and 15.8%, respectively) along with a small increase in SHBG levels (7.0%). Conclusions: In women using OCPs and SJW simultaneously, it appears that SJW does not interfere with the antiandrogenic properties of OCPs. (c) 2006 Elsevier Inc. All rights reserved.