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’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.