Scarleteen

Hello,
I am on cyclen birth control pills and take them diligently. I was put on Cerfuroxime 500 mg tablets (cifton) for a flu that I had. The doctor did not mention if I needed to use a backup method, and when I searched what antibiotics react with birth control pills it only came up with tuberculosis. I took my birth control pills and antibiotics at the same time of day (I had to take my antibiotics at night time.) My friend told me I may be at a risk for pregnancy so I went in and talked to a pharmacist and they said I should “probably” take plan b since my antibiotics could decrease my birth control (I had sex in less than 24 hours without any other protection besides the pill.) I am unsure if I needed to take plan b, and if I continue with my birth control pills or if I put a hold on them until I get my period? Since I took plan b? I only have one more pill in the pack left. Do I take it tonight or wait till my period comes? (The pharmacist seemed unsure about this and told me to not take my last pill so I could see if I missed a period from being pregnant or from the birth control). I was on a different pill brand but switched it for this pack so I have had some bleeding (I did not take any breaks between switching pills).
Thank you

I was also wondering if alcohol can affect plan b?
Thank you[/quote]

Hi amandat12,

Your friend is correct that the antibiotic that you were prescribed, Cerfuroxime, may make birth control pills less effective. It's a bit confusing because some antibiotics interfere with birth control pills, some *may* interfere with birth control pills, and others definitely don't. You doctor should have told you that Cerfuroxime is one of the ones that may interfere--I'm sorry that they didnt.

This article outlines what does, what might, and what does not make birth control pills less effective: Something You Can Worry About Less: Interference and Hormonal Birth Control. You are right that the antibiotic used to treat tuberculosis is one of the medications that *does* make birth control pills less effective.

As the article mentions, "Current research indicates that almost all antibiotics have no effect on the efficacy of hormonal birth control. However, much of this research has included sample sizes considered too small to detect a rare interaction that may occur in less than 1% of users. So if you are taking an antibiotic, your decision to take more precautions depends on how much risk you are or are not comfortable with. Keep in mind also that if you are taking an antibiotic, your body is probably also battling an infection, which makes you more susceptible to other infections like STIs. The bottom line: if you are someone who wants to minimize these risks as much as you can, consider using condoms as a backup."

So the good news is likelihood is low that pregnancy will occur. But if you want to be safe, you should go ahead and take Plan B or another form of emergency contraception. Drinking alcohol does not make emergency contraception pills less effective. Here is more information about emergency contraception: Emergency Contraception (Plan B or the Morning-After-Pill).

In terms of whether or not you take the last pill in the pack, it sounds like the pharmacist didn't have a strong opinion. I don't think it could hurt to take the last pill. Whatever you decide to do, seems like backing up with condoms would be a sound choice for the next few weeks.

Will the antibiotic affect the effectiveness of plan b?