It has two components. While Rifampicin and Rifabutin (and Penicillin,Amoxi and a few others) are directly showing effects on the contraceptives drugs effects, there is another factor that shouldn’t be underestimated:
ABs can and will cause digestive symptoms, fastening gastric passage and that alone is known to reduce the effectiveness of hormonal contraceptives countless times.
It’s easier to tell people to just use a rubber when on antibiotics rathern than explain to them that it’s only for some unpronounceable substances for most of the population and have them memorize a list of substances for which it’s safe to go on as usual - azithromycin is safe, amoxicillin is not. They may sound fairly similar to a layman.
It’s because some substances (in this case, antibiotics) mess with the units in your body that process them and prepare them for excretion. They may inhibit or induce them, but these units process a whole load of other stuff. Including birth control, which can lead to less activity from the birth control pills because they’re inactivated quicker (in case of induction) or the biotransformation to the active form is slower (in case of inhibition, for prodrugs that are inactive as is, but have active metabolites, no idea if this is the case for birth control though).
A similar thing happens with alcohol, for example, which is why you should always be honest with exactly how much alcohol you drink or what other drugs you take when talking to an anaesthesiologist, or any doctor prescribing you any sort of medicine, lest you risk ineffective anaesthesia or treatment (the first one is worse imo).
That’s not really true.
Sure it’s true for rifampicin and rifabutin (and maybe one more similar one). But those are used to treat TB.
All the standard ones you’d take are fine for birth control.
Edit: Thanks to some people who are more knowledgeable than me on the topic, there are some others, or secondary effects you should consider.
Moral of the story: if in doubt ALWAYS use more contraception. Best to be safe out there.
It has two components. While Rifampicin and Rifabutin (and Penicillin,Amoxi and a few others) are directly showing effects on the contraceptives drugs effects, there is another factor that shouldn’t be underestimated: ABs can and will cause digestive symptoms, fastening gastric passage and that alone is known to reduce the effectiveness of hormonal contraceptives countless times.
That is true. I didn’t think of it from that angle. I haven’t read too much into that. But now I will. Thanks for the info.
For the record, always use secondary contraception if you’re in doubt. I should have said that in my first post.
According to Mayo Clinic, penicillin and amoxicillin also can make birth control less effective. But most other sources agree with you. I wonder if it’s relatively new information that those antibiotics don’t affect it or what.
It’s easier to tell people to just use a rubber when on antibiotics rathern than explain to them that it’s only for some unpronounceable substances for most of the population and have them memorize a list of substances for which it’s safe to go on as usual - azithromycin is safe, amoxicillin is not. They may sound fairly similar to a layman.
It’s because some substances (in this case, antibiotics) mess with the units in your body that process them and prepare them for excretion. They may inhibit or induce them, but these units process a whole load of other stuff. Including birth control, which can lead to less activity from the birth control pills because they’re inactivated quicker (in case of induction) or the biotransformation to the active form is slower (in case of inhibition, for prodrugs that are inactive as is, but have active metabolites, no idea if this is the case for birth control though).
A similar thing happens with alcohol, for example, which is why you should always be honest with exactly how much alcohol you drink or what other drugs you take when talking to an anaesthesiologist, or any doctor prescribing you any sort of medicine, lest you risk ineffective anaesthesia or treatment (the first one is worse imo).