Antibiotics & Birth Control: Can You Get Pregnant?

Question
Dear Dr. Solberg,

My query is in regards to birth control and antibiotics.

I currently take Valette and have for almost 2 years, recently I have been on the antibiotics Keflex, Flagyl and azithromycin, all of which I have finish on or before Monday just gone.

If I have sex with my partner this Saturday (5 days following discontinuation of antibiotics) would we be protected from pregnancy? (We also used the withdrawal method effectively in combination with the pill in normal circumstances)

Thank you and Kind Regards,

Molly

Answer
Most antibiotics don't have very much effect on birth control pills, but perhaps taking all 3 might decrease effectiveness.  If so, you would be fully protected 7 days after stopping the antibiotics.  Most likely you're protected 5 days after stopping, but I can't say for sure.  Using effective withdrawal should keep you protected.  Normally while on the pill, withdrawal isn't really necessary, as long as you don't miss any pills.