Metronidazole and Birth Control

[busylizzie]

Hi, I've been prescribed Metronidazole for bacterial vaginosis. I went the doctors yesterday and I'm picking up my antibiotics today. I've been prescribed a single 2g dose of it to be taken all at once. I have a couple of questions:

1. I drank a fair amount of wine last night and I feel rough because of it - do you think I should take the antibiotic tomorrow just to be safe in case there's still alcohol in my system because I know the two can interact really badly

2. I take Levest combined oral contraceptive pills. I just finished a pack yesterday and will be expecting my withdrawal bleed Monday. I'm confused about what extra precautions I need to take to prevent pregnancy since the Metronidazole will be in my system during my period - so does this mean I'll be fully protected next cycle? And if I were to have sex this period week, I'l need to use condoms right? Will I need to use condoms in my next pill cycle too?
Another thing that's confusing me is the NHS website (I live in England) says that Metronidazole doesn't interact with birth control and my doctor also said it would be fine, but you guys suggest it may interact. So shall I err on the side of caution?

Thanks so much for your help xx

[Ashleah]

Hi Busylizzie,

It is best to consult the doctor who prescribed you medication when you pick up your medication! They can give you the best information. Also check in about having vaginal sex while being treated for an infection. I think it is advised to finish your treatment before engaging in sex again. Not for fear of pregnancy, but so the infection can heal. New studies do suggest there are very few antibiotics that intefer with birth control, but if it would make you more comfortable to back up your method there is nothing wrong with having that security (IF your doctor says it is okay to have sex, otherwise hold off )

[busylizzie]

Hi - I went to the pharmacy and the pharmacist was quite unhelpful with regards to my questions saying vaguely that the antibiotic may interfere but hes not sure. He was also quite horrible to me actually saying I should be thinking about clearing the infection, not sex. But I'm mainly concerned that I'll get pregnant - I can obviously leave sex for a while I dont mind!
So basically, I have had sex yesterday - will taking this antibiotic today mean I'm more likely to fall pregnant because of the recent sex? Or would it only be after I start taking the antibiotic that I'd be more susceptible to pregnancy? I'm really confused.
Also, does being on my pill free week have any bearing on my likelihood or not to fall pregnant on this antibiotic?
I think I'll not have sex for a while to be sure the infection goes away and also to keep myself protected from pregnancy - how long would I need to abstain from sex or use additional contraception for?

Thanks for all your help and I hope this makes sense - I'm mainly just really confused because I seem to be hearing different things from all different places :/

[Johanna]

I am sorry the pharmacist was so unhelpful and judgmental

So, you do not have to worry about sex that you had before starting the antibiotic. Even if it does compromise your protection, it won't do so retroacticely. If you want to be on the safe side, you can back up with a condom while you take the antibiotic. If you finish before your placebo week is over, you can rely on your pill again when you start the new pack.