Birth Control And Antibiotics: Everything You Need To Know

birth control and antibiotics

In this article, we discuss how antibiotics affect birth control options.


Birth control pills have a success rate of 91% to 99% when used correctly. Most of the females today choose the hormonal contraceptive to stay protected from unwanted pregnancy.

The pill has other health benefits as well. Doctors can prescribe a birth control pill to regulate periods, reduce acne, alleviate PCOS symptoms, and decrease menstrual pain and heavy bleeding. Moreover, the administration of birth control pills can also prevent ovarian/uterine/endometrial/cervical cancer.

But, the effectiveness of the hormonal contraceptive can reduce if you are on certain antibiotics. If both the treatments go along together, then there could be problems. You must be wondering how antibiotics affect the efficacy of oral contraceptive pills. Or, you must be thinking if any other medicines impact the function of a contraception method? Let us first know how hormonal birth control methods work.

  • A birth control pill/patch/ring thickens the cervical mucus so that the sperm does not fertilize an egg.
  • It also stops the ovaries from releasing an egg.
  • The hormonal contraceptive then thins the uterine lining and disables implantation of a fertilized egg (if any).
  • All these three processes help you stay protected from unwanted pregnancy.

In the following post, we will discuss how antibiotics and birth control pills influence each other. We will also discuss how females can prevent an unplanned pregnancy when using certain other medicines and antibiotics.

Impact of Antibiotics on Birth Control

Antibiotics can interfere with the effectiveness of birth control pills, ring, and patch in two ways. An antibiotic can lower the estrogen hormone levels in your blood. It can also interrupt the function of how the hormones get processed in the liver. The birth control pill, ring, or patch contains the synthetic version of estrogen hormone. This synthetic version is known as Ethinyl estradiol. It is this hormone that suppresses ovulation and disallows an occurrence of pregnancy.

1. Antibiotics Affect the Liver Function to Reduce Their Efficacy

The liver is a vital organ. It processes everything your body gets, including birth control hormones. It also processes substances from other medicines. Specific antibiotics may increase the liver’s capacity and speed of breaking down the estrogen hormone from the contraceptive.

  • If an interacting antibiotic is taken. When using hormonal birth control. Then the ability of the contraceptive to stop an unwanted pregnancy decreases.
  • This may result in an unintended pregnancy. This is because of the concurrent treatment of a contraceptive and the interacting antibiotic.

2. Antibiotics Affect the Estrogen Amount For Re-circulation In Body

An interactive antibiotic can also reduce estrogen amount available to be re-circulated in the body, the process of estrogen re-circulation is known as enterohepatic cycling. When the liver breaks down the estrogen in the pill, it converts the hormone into chemicals. This chemical is released from the liver in the form of bile. The chemical in turn gets absorbed by the intestines. The bacteria in the gut turn these chemicals into active estrogen. Thus, the body then reabsorbs the active estrogen back from your intestines.

  • Your body is made up of billion types of good bacteria. These bacteria help in several important biochemical processes in the body.
  • The antibiotics kill the bacteria responsible for an infection. But, in the process, it may also kill the good bacteria. A number of good bacteria are found in the intestines. The good bacteria are in danger when certain antibiotics interact.
  • The entero-hepatic cycling process is done with the help of good bacteria. Taking antibiotics then interferes with this process.
  • Thus, birth control pills’ effectiveness decreases. This can lead to an unintended pregnancy even if you use the birth control method correctly.

Which Antibiotics Interact With Birth Control?

An antibiotic can carry different names depending on the brand. It is important to ask the doctor if the antibiotic prescribed has the potential to interact with a birth control pill, patch, or ring. A doctor can prescribe different types of antibiotics to deal with different infections. Sometimes, an infection could be severe. For this, the doctor can put you on antibiotics for a long term. As per evidence, only two types of antibiotics show a negative effect on hormonal contraceptives. These antibiotics are Griseofulvin and Rifampin.

A healthcare provider may prescribe Rifampim to treat tuberculosis. Do note that topical antibiotics have no interaction with birth control pills. A few reliable pieces of research also prove the levels of birth control steroids do not change when combined with some of the antibiotics. Such antibiotics are unable to impact the hormone level in the blood after administration of the pill.

So, here is a list of antibiotics safe enough to be taken when continuing with oral contraceptive medicine:

  • Roxithromycin
  • Ciprofloxacin
  • Ampicillin
  • Tetracycline
  • Clarithromycin
  • Temafloxacin
  • Metronidazole or Flagyl
  • Doxycycline
  • Ofloxacin

Apart from antibiotics, there could be other medicines that may make birth control pills less effective. You should consult a physician on the medicines that may interact with each other, especially the contraceptive medication. When you stop or start a medicine, you can request your doctor to run a check for medication interactions.

  • Some of the seizure medicines and anticonvulsants can interfere with the working of oral contraceptives. These interacting medications include phenytoin (Dilantin), Phenobarbital, primidone (Mysoline), and carbamazepine (Tegretol).
  • Griseofulvin is an antifungal medicine. It may reduce the success rate of hormonal birth control medicines.
  • St. John’s Wort also reduces the effectiveness of the pill.
  • Other interacting medicines with the pill include those for depression and diabetes.
  • Some of the HIV medicines may also negatively affect the birth control pill.

What Can You Do?

Hormonal contraceptives are one of the most effective to prevent pregnancies. For best results, you need to however take the pills or use a relevant contraceptive, consistently. For instance, if you are on the pill, then it gives the best result when you take it every day at the same time. This way, the pill has a success rate of 99%. But, if used incorrectly, like missed dose, or not taking on the same time every day, then the success rate reduces to 91%.

  • If you add to other medications in the process, then the chances of interactions increase. This could be any other medicine, including antibiotics.
  • Then the risk to an unintended pregnancy also increases. So, if you are using other medicines and antibiotics, remember, these could interfere with birth control pills.
  • When on other medicines with birth control pills, you must add a backup method of contraception or not indulge in intercourse at all.
  • While abstinence may seem a bad idea, you can use a condom along with the hormonal contraception measure. A condom or spermicide can improve the efficacy of contraceptive pills.
  • Even if you miss just one pill, a backup method is necessary. Otherwise, the antibiotics can further disrupt the efficacy of the pill.

Final Words

Even if antibiotics may reduce the pill’s efficacy, oral contraceptives are one of the safe bets to prevent an unwanted pregnancy. You can speak with your doctor about the ongoing medicines and choose the safest contraception method to go with the current treatment. If hormonal medicines are not your thing, then you can even switch over to non-hormonal birth control methods such as spermicide, condom, copper IUD, etc.