ask your pharmacist

Do antibiotics interact with birth control pills?

Antibiotics that have been shown to interact with birth control pills include rifampin (brand name Rifadin), and to a lesser extent, penicillin (Veetids), amoxicillin (Amoxil), ampicillin (Omnipen), sulfamethoxazole/trimethoprim (Septra or Bactrim), tetracycline (Sumycin), minocycline (Minocin), metronidazole (Flagyl), and nitrofurantoin (Macrobid or Macrodantin).

To help women avoid pregnancy while taking an antibiotic - and for at least one week afterward - doctors generally recommend they use a condom or spermicide as a back-up method of birth control. If you are taking both antibiotics and birth control pills, be sure to check with your doctor about how long you should continue to use a back-up method. Also, discuss any other questions you may have about this information.

Sources:
Dickey, R.P. Managing Contraceptive Pill Patients. EMIS Inc.,1998.
Hansten, P.D, J.R. Horn. Drug Interactions Analysis and Management, Applied Therapeutics, 2000.
Dipiro, J,T, Pharmacotherapy A Pathophysiologic Approach. Fourth Edition. Appleton &Lange. 1999.
Health. “Birth Control Pills”. http://www.mayoclinic.com. Mayo Clinic Health. Last accessed 11/15/2006.

This answer prepared 3/18/2001.
This information updated 11/15/2006.

• penicillin
• amoxicillin
• ampicillin
• sulfamethoxazole/trimethoprim
• tetracycline
• minocycline
• metronidazole
• nitrofurantoin