Levonorgestrel and Antibiotics: What You Need to Know About Interactions

When you’re taking levonorgestrel, a synthetic hormone used in birth control pills, patches, and IUDs to prevent pregnancy, and your doctor prescribes antibiotics, medications that kill or slow down bacteria causing infections, it’s natural to wonder: does this ruin my birth control? The short answer? Most antibiotics don’t. But one big exception does—and it’s not what most people think. Rifampin, a powerful antibiotic used for tuberculosis and other serious infections is the real troublemaker. It speeds up how your liver breaks down levonorgestrel, lowering hormone levels enough to risk pregnancy. Other common antibiotics like amoxicillin, doxycycline, or azithromycin? They don’t do this. Yet, confusion keeps spreading because of old myths and vague warnings.

Here’s the thing: levonorgestrel works by keeping your body from ovulating and thickening cervical mucus. If your liver starts metabolizing it too fast—like when rifampin is in the mix—you’re not getting the full dose. That’s why women on rifampin are told to use a backup method, like condoms, during treatment and for a week after. But if you’re on a standard antibiotic for a sinus infection or strep throat, you’re probably fine. The FDA and major medical groups have reviewed this repeatedly and found no strong evidence linking common antibiotics to birth control failure. Still, some people get sick while on birth control and start doubting everything. If you’re vomiting or having severe diarrhea from an infection, that’s a different story—it can stop your body from absorbing the hormone properly, regardless of antibiotics. And if you’re taking other meds like seizure drugs, HIV treatments, or St. John’s Wort, those can interfere too. The real risk isn’t the antibiotic itself—it’s the combo.

So what should you do? First, always tell your doctor you’re on hormonal birth control before they prescribe anything. Second, if you’re given rifampin or rifabutin (a similar drug), ask about backup contraception right away. Third, if you’re unsure, use condoms during the antibiotic course and for seven days after. Don’t panic over a simple course of amoxicillin. But don’t ignore the real risks either. This isn’t about fear—it’s about knowing what actually matters. Below, you’ll find real-world insights from people who’ve dealt with this, studies that cleared up the confusion, and practical tips to make sure your birth control stays effective no matter what else you’re taking.