The effects of antibiotics on birth control pills (oral contraceptives) may be overstated — except in the case of one antibiotic, rifampin. Studies clearly show that rifampin decreases the effectiveness of birth control pills in preventing ovulation.
Anecdotal evidence suggests this effect may also occur with other antibiotics, such as:
- Amoxicillin
- Metronidazole
- Tetracycline
- Cephalexin
- Erythromycin
- Isoniazid
No large studies have proved this effect. But researchers can't rule out the possibility that this may occur in a small number of women. If you're concerned, consider using a barrier method of contraception while taking antibiotics.
