exactly how much does antibiotics effect HBC?

[imnotyourstarx.livejournal.com]

i know antibiotics can mess with your hormonal birth control. but how much, exactly?

im on ortho evra.
i have an infected ingrown toenail. (it hurts like a bitch! my father's side of the family has weird shaped toes that are prone to ingrowns, and lucky me, i inherited them...) so im on stuff to kill the infection.

i did not pick up the presciption, since i was at work. i sent my companion to fetch it for me, with explicit instructions to ask the pharmacist what its going to do to my BC. the answer that he reported to me was, "its going to hurt it a little bit. like if its 97% effective, it might knock it down to, like, i dont know, 94ish, maybe?"

WHAT?! could you get any more vague? i already KNOW its going to knock it down a little. in fact, i was the one that told YOU that! i wanted you to find out the exact percentage! i wanted real stats! bahhh...

anyways. hopefully you guys are more keen on these things that he is.

Comments

[agata.livejournal.com]

Is it even possible to fins out the "exact" percentage. I've always been told from doctors/nurses that it becomes "ineffective" ... I really wouldn't trust any "exact" answers.

[imnotyourstarx.livejournal.com]

a ballmark (one not made up off the top of my boyfriend's head) would be ok. i mean, are we talking lowering it by 3% or 87%? because ill take the 3% lower chance. but not the 87%.

[queensugar.livejournal.com]

Unfortunately, there's actually no clear answer on how most antibiotics affect the birth control pill. So while the pharmacist really is being vague, s/he was also, more or less, making that figure up.

Studies have shown that only the antibiotics rifampicin and rifabutin can be proved to interfere with how oral contraceptives are absorbed into your system.

For all other types of antibiotics, the evidence is inconclusive, as you can read on this excellent set of guidelines. (http://www.ffprhc.org.uk/admin/uploads/DrugInteractionsFinal.pdf) (If you scan down a bit, there's a thorough discussion on antibiotics and oral contraceptives.) Some studies have shown that all other antibiotics do not affect how the pill is metabolized, and thus do not affect protection; other studies have shown that there was a difference.

So basically -- while the antibiotics may well not knock it down a little, they also may... we really don't have any definitive data available at this point to say one way or another.

If you want to play it very safe, you can use backup protection during your antibiotic treatment, and for seven days afterward. If you're not too worried about it, chances are that the antibiotics (provided they're not rifampicin or rifabutin) will not make a huge impact in your level of protection.

[imnotyourstarx.livejournal.com]

well, im on ortho evra, so its not oral contraceptives at all. :) but i do see your point. im not really worried, im more curious, i supposed.

[queensugar.livejournal.com]

Hehe yeah, I noticed that after I commented. A little slow on the uptake today, I am. :P

[imnotyourstarx.livejournal.com]

hehe noooo problem. like i said, im more curious than worried. we had sex this afternoon and he pulled out. people like to rag on the withdrawal method, but with that plus my HBC, even if its only, say, 90% effective as of now, its enough for me.

[queensugar.livejournal.com]

Well, I wouldn't be one to rag on that -- in my last relationship, I used it as my sole form of contraception for almost 2 years, and as soon as my current partner has practiced enough to do it reliably, I'll be quitting HBC and using it as my sole form again. :)

Combining HBC with withdrawal really is a nice, easy method of back-up protection that can reduce even a tiny risk of pregnancy considerably.

[imnotyourstarx.livejournal.com]

im personally a huge fan of the withdrawal method. i hate that it has such a bad reputation. my guy is a freakin pro at it. he should teach a class.

[frolicnaked.livejournal.com]

I would like to see this class.

I'm not particularly interested in using withdrawal in my own sex life (though I have nothing against it in general); I just would like to see this class. ;)

[queensugar.livejournal.com]

I will add to this: if you scan down to page 143, note 18 of that PDF file, you'll see this recommendation:

A combined oral contraceptive patch user taking a short course (< 3 weeks) of non-liver enzyme-inducing antibiotics (except tetracycline) should be advised to use additional contraceptive protection, such as condoms, during the treatment and for 7 days after the antibiotic is stopped. If there are < 7 days remaining before her patch-free week, another patch should be applied when due for changing and the patch-free week delayed by 7 days.