Due to its antagonistic effects on the GABA receptor in the central nervous system, supplementation with pregnenolone could cause problems in people with a history of seizures. Pregnenolone supplementation may increase the levels of progesterone and DHEA in the body and possibly the levels of other hormones (testosterone and estradiol). In theory, pregnenolone could cause disturbances in the endocrine system, which may manifest as changes in the menstrual cycle or the development or aggravation of hormone sensitive diseases (including breast and prostate cancer). The side effects and interactions with other therapies are currently unknown.