Do Antibiotics Affect Birth Control?

The Centers for Disease Control and Prevention (CDC) found that between 2017–2019, 65.3% of people with a uterus in the United States were currently using a method of contraception.

If you are using hormonal contraceptives, you may wonder if antibiotics can stop your birth control from working. The good news is the vast majority of antibiotics do not affect contraception. However, other prescription medications and herbal remedies may have an impact on their effectiveness.

In this article, you will discover the types of medication that can affect hormonal contraception and how to take birth control so it can be effective.

Close-up of woman pouring pills into palm of hand

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Antibiotics and Birth Control

Antibiotics like amoxicillin won’t affect the effectiveness of your birth control. The antibiotic rifampin (also known as Rifadin and Rimactane) is the only exception—it can lower the effectiveness of the pillbirth control patch, and NuvaRing.

So unless you’re using one of those birth control methods and taking rifampin, which is a medicine used to treat tuberculosis, you have nothing to worry about.

Side Effects

Rifampin can speed up the liver’s ability to break down molecules and medications, including hormonal birth controls, which are processed through the liver. This decrease in hormone levels can affect whether ovulation is prevented.

For this reason, anyone taking any form of hormonal contraceptive who is prescribed rifampin treatment should note that their hormonal contraceptive will not be as effective, and may increase their likelihood of becoming pregnant. 

While taking this antibiotic, you may want to use a backup form of birth control, such as a condom or diaphragm. Your healthcare provider should also alert you to this side effect when rifampin is prescribed.

Rifampin does not interact with other forms of birth control, such as contraceptive injection, and intrauterine devices (IUDs), meaning that you can continue to use these types of contraceptives while undergoing rifampin treatment.

Medication and Birth Control

Some other medicines besides antibiotics can make birth control less effective. The use of prescription medication is high. The CDC found that between 2015–2016, 50% of the female U.S. population used one or more prescription drugs in the past 30 days.

It’s important to be honest when talking to your nurse or doctor about what medicines you’re on so they can offer you the right contraceptive choice for your situation.

HIV Medication

Some medications that treat HIV may interfere with the pill. They include:

  • Prezista (darunavir)
  • Sustiva (efavirenz)
  • Kaletra (lopinavir/ritonavir)
  • Viramune (nevirapine)

Talk to your healthcare provider about what form of contraception is best for you if you are taking medications for HIV.

Seizure Medication

Birth control medication shouldn't interfere with how well your anti-seizure drugs work. But some of these medications increase the breakdown of the hormones in birth control pills. That could make them less effective. These drugs include:

  • Tegretol, Tegretol XR, Carbatrol, Equetro (carbamazepine)
  • Felbatol (felbamate)
  • Lamictal (lamotrigine)
  • Trileptal (oxcarbazepine)
  • Phenobarbital
  • Dilantin (phenytoin)
  • Mysoline (primidone)
  • Topamax (topiramate)

Be sure to use another form of birth control (like an IUD, a diaphragm, or a condom) if you are taking an anti-seizure medication.

Antifungal Medication

Antifungal medications may also lower the effectiveness of the pill, though the World Health Organization states that people taking hormonal contraception should be able to safely use these medications.

Antifungal medications that have been associated with contraceptive failure are:

  • The oral suspension Mycostatin, Nilstat, Nystex (nystatin), which is used to treat yeast infections
  • Fulvicin, Grifulvin V, Gris-Peg, Grisactin (griseofulvin), which is used to treat fungus infections of the skin, hair, scalp, and nails, as well as ringworm, jock itch, and athlete's foot
  • Extina, Nizoral (ketoconazole), which is used to treat fungus infections such as athlete's foot, jock itch, ringworm, and seborrhea (dry, flaking skin or dandruff)

Sleep Disorder Medication

Provigil (modafinil) is a stimulant that is usually used to treat the symptoms of sleep disorders like narcolepsy and sleep apnea. Provigil may reduce the effectiveness of your birth control, so use another form of birth control while you're on this drug and for a month after you come off of it.

If you struggle with falling asleep at night, you may be taking a sleep aid like melatonin to get some rest. Certain birth control types may have a minor interaction with melatonin, and increase the melatonin's effect, so be sure to start with low doses and monitor for excess sleepiness if you are on both.

If you take birth control, you should discuss your sleep-aid options with your healthcare provider.

Herbal

In addition to prescription medications, certain supplements have been shown to lower the effectiveness of hormonal contraception.

  • St. John's wort: This herbal or dietary supplement is promoted for improving mildly depressed mood and as a sleep aid. St. John's wort can affect estrogen breakdown and cause you to experience breakthrough bleeding. 
  • Flaxseed: These seeds contain plant estrogens that can potentially disrupt your body's ability to absorb some or all of the hormones in birth control pills.
  • Saw palmetto: This supplement, which is typically taken to raise testosterone levels, can decrease the effects of estrogen in the body and make some combined birth control pills less effective.
  • Alfalfa: This herb can affect your body’s absorption of the hormones in birth control pills, making them less effective.

All of these supplements are best avoided if you use the pill as your only form of birth control.

How to Take Birth Control Correctly

The pill has the potential to be 99% effective at preventing pregnancy if you take it without fail—meaning you don’t forget to take the pill for even a day or two.

Taking the pill perfectly can be difficult, which is why 9 out of 100 people who use the pill will have an unintended pregnancy every year. The pill is most reliable when you take it consistently at the same time each day. Being consistent helps keep hormone levels from fluctuating.

Summary

With the exception of the drug rifampin, there’s little evidence that antibiotics interfere with birth control pills. Other prescription medications and herbal remedies may make birth control not work as well, including seizure medications, HIV drugs, antifungal medications, and sleep disorder medications.

A Word From Verywell

When you are discussing birth control methods with your healthcare provider, make sure you bring an updated list of the medications and supplements you are taking. This will help them make an informed decision about the best form of birth control for you.

Unless you are taking the drug rifampin for tuberculosis, there's little evidence that antibiotics interfere with birth control pills. More research is definitely needed in this area. To be on the safe side, always check with your healthcare provider and consider using a backup form of birth control while taking antibiotics.

Frequently Asked Questions

  • How does birth control work?

    Hormones in birth control pills prevent pregnancy by stopping or reducing ovulation (the release of an egg from an ovary), thickening cervical mucus to keep sperm from entering the uterus, and thinning the lining of the uterus so that a fertilized egg is less likely to attach.

  • How effective is birth control?

    The pill has the potential to be 99% effective at preventing pregnancy if you take it without fail—meaning you don’t forget to take the pill for even a day or two.

  • How long does birth control stay in your system?

    In general, most birth control methods don't stay in the body for very long after you stop taking them. In the case of hormonal birth control methods such as the pill or an IUD, it takes about 24 to 48 hours after discontinuation for the hormones to leave the body.

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10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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