# Oral Contraceptives and Antibiotics

**URL:** <https://boards.straightdope.com/t/oral-contraceptives-and-antibiotics/468959>\
**Category:** Factual Questions\
**Created:** [October 21, 2008, 10:19pm UTC](https://boards.straightdope.com/t/oral-contraceptives-and-antibiotics/468959 "2008-10-21T22:19:00Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![Hello\_Again](https://avatars.discourse-cdn.com/v4/letter/h/85e7bf/32.png) [@Hello\_Again](https://boards.straightdope.com/u/Hello_Again)\
**Post date:** [October 27, 2008, 12:33am UTC](https://boards.straightdope.com/t/oral-contraceptives-and-antibiotics/468959/21 "2008-10-27T00:33:11Z")

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> [@irishgirl](#):
>
> My personal theory is that the sickness the antibiotics are prescribed FOR might be equally to blame:  
> When you’re nauseated and sick, you might not feel like taking tablets, especially if sex is the last thing currently on your mind…too bad when 5 days later you feel better and you’re unexpectedly fertile.  
> .

But it’s crazy to say that antibiotics were the “cause” of the failure in that case. It’s like saying, if you stay out late one night drinking, and miss your pill the next morning because you overslept, that alcohol “caused” your OCP to fail. Not taking your pill caused your OCP to fail.

But then, I’m the kind of pill taker who has never (in 10 years) “just not felt like” taking my pills on time. In general, I “just don’t feel like” getting pregnant a hell of a lot more. I think the most I’ve been late is 12 hours , and I’ve never erred twice in a cycle, ever.

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**Author:** ![Harriet\_the\_Spry](https://avatars.discourse-cdn.com/v4/letter/h/e56c9b/32.png) [@Harriet\_the\_Spry](https://boards.straightdope.com/u/Harriet_the_Spry)\
**Post date:** [October 27, 2008, 12:52am UTC](https://boards.straightdope.com/t/oral-contraceptives-and-antibiotics/468959/22 "2008-10-27T00:52:59Z")

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One might expect to see a decline in fertility and frequency of sex due to illness. A UTI, sinus infection, etc. can certainly put someone off their game. If we assume illness correlates with antibiotic use, we would then expect the OCP+antibiotic pregnancy rate to be lower than the OCP only rate. If the rates are equal, that \*could \*indicate reduced effectiveness of the pill. I wonder if studies take that into account?

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