Getting sick with a bacterial infection while on birth control may make some women a little nervous. This is because they may have heard that some antibiotics may lessen the effects of birth control. If you need to take antibiotics and birth control together, you need to know the proper information about any drug interactions. Let’s discuss why certain antibiotics may make your birth control not work and if there are any alternative treatments available for bacterial infections.

Is It True that Antibiotics Make Birth Control Less Effective?

There is a lot of information floating around that antibiotics make birth control less effective. For the most part, most antibiotics will not affect birth control. The list of antibiotics that most likely WON'T affect birth control are:

  • Tetracycline: Used for acne, tooth infections, Lyme disease
  • Cipro: Urinary tract infections, some ear infections, pneumonia
  • Penicillin’s: Strep throat, tooth infections, upper respiratory infections, ear infections
  • Flagyl (Metronidazole): Vaginal infections, some infectious diarrhea
  • Others like doxycycline and ampicillin

Scientists have researched the use of birth control with these antibiotics and have data that shows they do not change the effectiveness of birth control.

There is one instance where an antibiotic does interfere with birth control. If you have tuberculosis and are taking rifampin/rifabutinstudies show that this may lower the effectiveness of the birth control pills, patches and ring. You need to let your doctor know if you are on the pill if you are prescribed rifampin. You will probably be taking the antibiotic for around six to nine months for tuberculosis and your doctor may want to change your contraceptive method. If you choose to continue your current birth control method, it is important to use another form such as; a condom while on rifampin.

The reason women on birth control need to be cautious with other medications is that some medications change the way your body excretes the hormones. Birth control pills are designed to prevent you from ovulating by changing or stopping the hormonal process. Rifampin is one drug that alters your hormone metabolism and you could ovulate while taking it and become pregnant.

Lastly, there is a small number of women that any antibiotic changes the way their body metabolizes birth control and it may possibly have decreased effectiveness. While this is very rare, it may be a good idea to use another form of birth control during antibiotic therapy. It is too risky to guess if they will change your body’s response to birth control. One type of birth control that is affected by antibiotics is the “low-dose” type pill.

While most antibiotics are okay to use with birth control, it is always better to use added protection. If you need more information on antibiotics and birth control, just ask your doctor or pharmacist.

Other Medications That Can Interfere With Birth Control

If you become ill and need to see your doctor for medication, make sure you tell them everything you are taking including birth control. They will need to know about any over-the-counter medications, herbal remedies and prescription drugs. When you receive a new prescription medication, ask the doctor or pharmacy if there are any drug interactions with birth control just to be on the safe side.

Here are some of the other medications that can interfere with birth control:


Why They Interfere with Birth Control

Medications for St. John’s Wort

This herb is taken for depression or anxiety and can lower the hormone levels the body absorbs from the pill. This may cause spotting and/or ovulation. It is very important to use back-up birth control if you take this herb and let your doctor know you are taking it when you are prescribed birth control pills.

Epilepsy Drugs/Mood Stabilizers

Drugs such as Tegretol, Phenytoin, Primidone, Topamax and Lamotrigine can all reduce the effectiveness of birth control. Also, the birth control hormones may reduce the effectiveness of these medications and you might be at higher risk of seizures or manic swings. Make sure you discuss birth control and the use of epilepsy drugs with your doctor to avoid interactions. Your doctor will need to know you are on birth control so they can monitor your medication levels to prevent seizures.

Anti-Virals/HIV Drugs

HIV medications can reduce the effectiveness of the pill. This includes Darunavir, Nevirapine, Lopinavir, Tipranavir, Fosamprenavir and Nelfinavir. If you let your doctor know you are on birth control pills, there are other medications for HIV that will not affect the birth control pills. Make sure you use a back-up method for birth control while on HIV medications.

How to Make Birth Control More Effective

  • When you receive a prescription for antibiotics, ask your pharmacy if there are any medications that make them less effective.
  • Use another method of birth control while using antibiotics. If you use spermicide and diaphragm, there is almost 100% effectiveness.
  • Take birth control pills at the same time every day. Take them exactly how your doctor tells you to take them.
  • Do not skip pills when on birth control and follow any instructions to “catch up.”
  • If an IUD is your birth control method, make sure you check for placement every month. If you cannot find the attached string, you need to use another form of birth control and see your doctor as soon as possible.
  • If you have unprotected sex, you can contact your physician within 72 hours for emergency contraceptives.

It only takes one time having sex without protection to get pregnant. You may be lucky and not get pregnant, but that one time may be the time that you end up with an unplanned pregnancy. 

Video for More: How to Take Birth Control Pills for Better Results