Can amoxicillin (antibiotic) make birth control less effective?

Yes. Any antibiotic can make birth control less effective, since the antibiotics can kill off some of the "good" bacteria in the gut that are needed to process the birth control hormones. Backup methods are important while on antibiotics.

Related Questions

Can I get pregnant if I took amoxicillin and birth control and had sex on the second day of taking antibiotics?

Unlikely. When a woman is on birth control pills, starts antibiotics and has sex on the second day of antibiotics she is not yet at risk of pregnancy. Though antibiotics decrease the effectiveness of bcp a little the time of possible pregnancy is toward the end of the antibiotics and right after. But to be safe, use a back up form of birth control. Read more...

What is the interaction between birth control pills, the morning after pill, and the antibiotic amoxicillin? What's the possibility of pregnancy?

No interaction. If you are on birth control pills, took the morning after pill and are taking Amoxicillin for an unrelated reason, you are extremely unlikely to be pregnant. Check a home urine pregnancy test the after a missed period and if negative repeat in a week - that's the only way to be sure. Take Folic Acid 1 mg daily and best of luck! Read more...

Which of these antibiotics for cold interfere with Yaz (drospirenone and ethinyl estradiol) (birth control pills) - Cefalexin, Ospen, Amoxicillin, or any other in that category?

Penicillins mostly. Antibiotics may interfere with the effectiveness of birth control pills. Have they ever lead to failure of birth control? Not conclusively although it is theoretically possible. Mid cycle spotting could be a sign they are adversely affecting efficacy. Rifampin, Penicillins like Ospen and amoxicillin can do it. Cephalexin probably not. Stop them as soon as you can. Read more...