Antibiotics and birth control: What you need to know

When you first start taking antibiotics to treat an infection, sex might be the last thing on your mind. But it’s important to complete the course of medication even as you start to feel better. And if, in the meantime, you do find yourself in the mood, you’ll need to know whether the antibiotics you’re taking will impact your birth control. 

As certain antibiotics can impact the hormone levels in your blood, hormonal birth control — such as the pill, implant, or contraceptive patch — could be affected. Keep reading to find out when you don’t have to worry and when you’ll need to use backup protection with your hormonal birth control.

Key takeaways

• Most antibiotics are safe to take while on birth control, but you should always check with your doctor about the specific type you’re taking.
• The antibiotic you definitely need to be careful with is rifampin, which is known to make hormonal birth control less effective. You should also take precautions when using a similar antibiotic called rifabutin. Rifampin is used to treat infections like tuberculosis and meningitis, and rifabutin is given to patients experiencing ulcers or complications from HIV. 
• If you need to take rifampin or rifabutin, you should use barrier contraception (like a condom) for 28 days after you’ve taken your final dose.

Can you take antibiotics and birth control pills?

Yes, most antibiotics are safe to use with birth control, but it’s always best to speak to your health care provider about whether the type of antibiotic you need can affect birth control or not. They’ll be able to talk you through your options and establish whether or not you’ll need extra protection to prevent pregnancy. 

“Commonly prescribed antibiotics like penicillin, cephalexin, or doxycycline are safe to take with combined oral contraceptives,” says Flo expert Dr. Katharine Claire DeGeorge, associate professor of family medicine, University of Virginia, US. “These do not require a backup method.” 

It’s worth noting that, unfortunately, vomiting can sometimes be a side effect of taking antibiotics. And if you throw up while taking antibiotics and the pill, it could make the hormonal contraception less effective — even if the two medications are otherwise fine to take together. “If this happens, a backup method should be used until seven active pills are taken and kept down,” says Dr. DeGeorge.

Antibiotics that are safe with birth control 

Research suggests that any non-rifamycin antibiotic is safe to take with birth control and won’t increase the risk of pregnancy. Rifamycin antibiotics include rifampicin and rifabutin, which we’ll explore in more detail below.

Which antibiotics affect birth control?

It’s always a good idea to remind your doctor that you’re using hormonal birth control before they prescribe you antibiotics. They’ll be able to give you personalized information on what they’re prescribing (including whether it interacts) and potentially offer you an alternative.

However, there are two antibiotics to have on your radar that definitely do affect this type of contraception: 

• Rifampicin, also known as rifampin, is used to treat infections like tuberculosis and meningitis bacteria in the nose and throat. Although this antibiotic is not widely used today, it’s good to be aware of it just in case. And if you do need to take it, don’t panic, the extra precautions you need to take are quite simple, which we’ll explain in more detail below. 
• Rifabutin is also thought to make hormonal birth control less effective but to a lesser extent than rifampicin. This antibiotic is given to patients experiencing ulcers from an H. pylori infection or who have mycobacterium avium complex disease, a complication of HIV.

How rifampicin affects birth control

Let’s start with a quick recap on how hormonal birth control works. It contains the hormones estrogen and/or progestin, which work to prevent pregnancy by: 

• Preventing ovulation, which is when one of your ovaries releases an egg
• Thickening cervical mucus, making it harder for sperm to reach the egg
• Thinning the lining of your uterus so that a fertilized egg can’t attach and grow there (This is known as implantation.) 

Rifampin and rifabutin decrease the concentration of estrogen and progestin in your blood. Having a lower concentration of these hormones means their contraceptive effects might not work, which is why you should use backup protection. 

How antibiotics can impact your birth control all comes down to the way these particular antibiotics break down hormones in your liver. “Rifampin and rifabutin induce liver enzymes that result in decreased levels of the hormones that prevent pregnancy,” explains Dr. DeGeorge.

Contraceptives that are affected by rifampicin: 

• Oral hormonal contraceptives: These include the combined pill and the “minipill” or progestogen-only pill.
• The contraceptive implant: Usually in the upper arm, this small implant releases a gradual supply of hormones to prevent pregnancy. 
• The vaginal ring: This is a ring that sits inside the vagina and releases hormones to prevent pregnancy.
• Patches: Hormone-releasing patches that stick to the skin and are changed weekly are normally a good form of contraception, but they are affected by some medications.

Сontraceptives that are not affected by rifampicin:

The good news is not all birth control is impacted by rifampicin or rifabutin. Nonhormonal birth control is recommended and safe to use, including barrier methods like a condom, diaphragm, or the copper IUD. And some types of hormonal birth control, like the hormonal IUD or birth control shot, can also be safe to use with rifampicin or rifabutin.

What to do if you’re on birth control and taking rifampicin

You might be wondering whether doubling up on birth control pills will make them stronger and more effective, but this is a myth. If you’re taking rifampicin or rifabutin, you need to also use a form of barrier contraception that physically stops sperm from entering your uterus. These include:

• Condoms: A thin covering usually made of rubber or plastic that’s worn either over the penis (male condom) or inside the vagina (female condom). As male condoms are the most effective barrier method, doctors usually recommend these as backup contraception.
• A cervical cap: A small plastic dome that uses suction to fit tightly over the cervix
• A sponge: A round device made of soft foam that blocks sperm from entering the uterus 
• A diaphragm: A small, dome-shaped device that fits inside the vagina to cover the cervix  
• Vaginal gel: A prescription nonhormonal gel that blocks sperm from entering the cervix by changing the pH of your vagina

It’s important to keep using the extra protection until about a month after you’ve finished the course of antibiotics. “You should use a backup method until 28 days after the last dose of rifampin,” says Dr. DeGeorge. During this time, if you’re taking birth control pills, you should shorten your break week or hormone-free days to four days. It’s also important to tell your doctor if you’re planning on becoming pregnant or want to start breastfeeding on antibiotics. 

It can be stressful having to suddenly start using an extra type of birth control, especially if it’s one you’re not used to. Remember, your doctor is there to support you and can help you figure out the right form of barrier contraception for you, so don’t be afraid to ask questions.