Scarleteen

I was taking Amoxicillin which can decrease the effectiveness of the Lo Loestrin Fe I take. My question is if I backed up all while using the antibiotic and finished the first day of a new pack. I continued to back up for the seven days after using the antibiotic. My question is would my pill then still be effective?

Hi KJK2,

The best person to direct this question to is the healthcare provider who proscribed the amoxixillin to you. And, in truth, we recommend using the buddy method of condoms plus pill even when the pill isn't potentially compromised because it is more effective at preventing pregnancy (plus it protects against STIs). So you may want to keep backing up anyway

Well I called my pharmacist and she said the antibiotic would be out of my system by the third day after finishing the pill. Exactly seven days later I only had a situation with precum. I know precum is a low risk especially after the guy has urinated beforehand. I was just curious if the seven days of perfect pill use would offer an other protection? Also I've been on the pill for over 2 years

By all means, the pill offers additional pregnancy protection, even if and when it might be somewhat less effective due to something like a possible medication interaction.

So, it's not like your pill, even if the antibiotics DID interact, would go from being 91% effective in typical use to being 0% effective, unless you simply stopped taking it altogether.

So the antibiotics wouldn't substantially render the birth control useless is what you're saying? I just wouldn't have the full protection as I would normally with taking my pill at the same time everyday.

My other question is since it would be out of my system three days after finishing the antibiotic then taking the bc for an additional week after would my effectiveness be back up to around 94% (since 99.7% is more in lab studies) or is that something we just won't know?

Exactly. They just may, potentially, make it less effective.

We couldn't possibly guess at percentages like that, though. Again, this is a conversation best had with your prescribing physician or pharmacist (though they won't be able to give figures like that either, since to my knowledge, we don't have the studies to provide that kind of data, and since effectiveness for methods is figured for a year's time, it would be impossible, I'd think, to get figures like that for something like this that isn't about a full year).

Rather, figure that typical use rates factor in for things like -- in one year of use -- using antibiotics or a missed or late pill every now and then.

Alright thank you so much for clearing that up!

Sure thing!

I guess I didn't read as closely the last part haha. So the pill with use of antibiotic falls within the typical use category?

The pill plus an antibiotic known to impact its effectiveness would fall under typical use; if you're using any other antibiotic, as long as you're following the pill usage guidelines in all other ways, that's still perfect use.

Just to confirm and sort of just get a yes or no: still taking the pill while on antibiotics and only being exposed to precum would leave me with a low risk rather than a high risk because it is still using two methods?

Just to confirm and sort of just get a yes or no: still taking the pill while on antibiotics and only being exposed to precum would leave me with a low risk rather than a high risk because it is still using two methods?

If you mean using the pill plus withdrawl, then yes, that has a lower risk of pregnancy than using the pill and having someone ejaculate inside or on the vagina or vulva.