Can antibiotics affect a woman's monthly cycle?

Yes it can, and should be listed in the contraindications and side effects of your prescribed medication.

Thanks AmWiser!

Also bear in mind antibiotics can change the effectiveness of birth control pills, leading to changes in your cycle and fertility.

I have never heard of antibiotics changing a cycle, except theoretically it is possible if the woman is on birth control pills. I have taken super mega doses of antibiotics multiple times in the last 10 years, intravenous and by mouth and I have never once had a cycle change. But, I guess being sick could affect someones cycle, and some people have much more sensitive cycles. Also, I know several people who finally became pregnant while on antibiotics after months of trying.

20yo male here and even I knew this.

They do indeed change the effectiveness of birth control pills. I’ve been sick many many times in my lifetime, but only when I was on some strong antibiotics did I get pregnant with my daughter (we weren’t even trying—I was on the pill.) My cycle itself never changed—the pill just wasn’t working quite as well.

When I first got pregnant, I kept trying to figure out if I missed a pill and when I figured out when she was conceived, it was when I was on antibiotics. It’s a year later now, and I’ve got a 10 week old baby.

Those of you who say antibiotics affect a woman’s cycle when she is not on the pill, do you have a reference you can cite? It makes no sense to me, except like I said that maybe being sick is a trauma to the body.

After a little more research, I’m about sure it “can”, not that it “does” in every instance but it can. Especially if it’s foreign to your body because you’ve never taken it or haven’t taken them in a long time, it can throw it off a couple days. I have NO scientific research but since I asked on here, I’ve talked to several women and I’ve heard some interesting stories. It’s also a pretty popular question on the web. Some scientific brainiac should look into it.