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Tufts OpenCourseware
Author: Kanchan Ganda, M.D.

1. Likelihood of Pregnancy and Last Menstrual Period (LMP)

Asking a patent a personal question about her period can be very embarrassing. So start out by telling the patient that dental radiographs are necessary before treatment and if any infection occurs during treatment, antibiotic use is required. “Prior to doing radiographs, we need to know if you are pregnant and when was your LMP. Also, antibiotics decrease the potency of oral contraceptives (OCs), so we need to know if you are taking birth control pills.”

This format gets you the answers you are looking for. Do keep in mind that even though ampicillin and tetracycline are the antibiotics most implicated in affecting birth control pills, all antibiotics reduce the potency of birth control pills. Patients on OCs getting antibiotics have to take extra precautions against getting pregnant, until the end of the NEXT CYCLE.

Levonorgestrel (systemic contraceptive) is not affected by oral antibiotic use.