The truth about antibiotics and birth control!

Q: I heard that antibiotics interfere with birth control pills, but I’m on the birth control that gets implanted under my skin – will antibiotics interfere with that too?

A: I’m so glad you asked this question!  This is one of the biggest medical myths of all time; one that gets propagated in doctors’ offices, health clinics, hospitals, blogs, magazines – and OK fine, student health centers – every day.  So now, for the first time ever… in print… online… on this blog… the TRUTH!

The only antibiotic that has ever been shown to interfere with birth control levels and effectiveness is a medicine called rifampin which is used to treat tuberculosis.  Rifampin may also interfere with the birth control patch and vaginal ring so if you are taking it, be sure to use a back-up, non-hormonal (i.e. condom) form of birth control.

There are some other medications that can interfere with your birth control, however, and if you are taking any of them you should always use back-up contraception.

  • Griseofulvin
  • Phenytoin (Dilantin)
  • Carbamazepine (Tegretol)
  • Phenobarbital
  • Topirimate (Topamax)
  • St. John’s Wort (herbal supplement)

But in general, your birth control will not be affected by any run-of-the-mill antibiotic that you might be taking for things like sinus infections, strep throat, urinary tract infections, skin infections, acne, etc.  Some people believe that because antibiotics disrupt the normal bacteria in the gastrointestinal tract, they will interfere with the absorption of the birth control pills from your stomach.  But this is not an issue, and even if it were, it wouldn’t apply to birth control methods that don’t involve swallowing pills like the skin patch or the vaginal ring or Implanon.

Now, there are enough women out there who swear that they have little antibiotic babies running around the house that your health care provider will probably still tell you to use back-up just in case.  And birth control doesn’t do anything to protect you against sexually transmitted infections, so using a condom is a good idea no matter what medications you’re taking.  But you can rest assured that your birth control is just as effective when you’re taking antibiotics as when you’re not. 

John A. Vaughn, MD (OSU SHS)

22 thoughts on “The truth about antibiotics and birth control!

    • There is contradicting information on birth control shots. Some say that they are not impacted by antibiotics and other say that they are. Better to be safe and use additional protection when on antibiotics.

  1. I was just prescribed Levofloxacin as an antibiotic. I noticed it wasn’t on your list but both the doctor and pharmacy tech informed me it could interfere with my birth control. Do you know anything about mixing these 2? I plan on using additional protection but just want to be sure it won’t do anything else to my body that I should worry about.

    • Don’t mix them!! Or use back-up, such as condoms during that month. You were lucky, you had doctor and pharmacy warm you. Noone told me.

  2. I been on my drop shot for over a year now I started April 2014 and just had one July 2nd I was put on amoxicillin for my tonsil infection and had unprotected sex.. I just start taking the pills and only had about 4 could this cause pregnancy?

  3. I was on Levofloxacin while on birth control, and I got pregnant. Noone told me that I should be careful when taking that medicine. I am SO upset. I already have two children, turning 40 next year. I don’t want another child. How can you say that it is not a conflicting drug???

  4. I have the implanon and i was just prescribed by my dentist Amoxicillin 500mg and Tylenol 3. Will these two combinations affect my birth control?

  5. I’ve been on the nexplanon for almost two years now I was just prescribed cephlaxen for a rash I got on my arm. Does this affect the effectiveness of my birth control? Should I use a back up?

  6. Just started taking cephalexin 500 MG capsules and earlier today I started my birth control again ( unvaring ) and I’m wondering if the antibiotics will interfere with my birth control? Thanks in advance!

  7. Hey I know someone already metion this but I got the birth control shot and I had a UTI recently,Does the anti boitics for my UTI effect my birth control? I currently afraid cuase I just unprotected sex and I’m worried that what I heard is true.

  8. I have an implanon hormonal implant and I am taking cloxin antibiotic for 7 days will it decrease implant hormonal effectiveness?

  9. I’m on the drop shot right now and get the implant tomorrow morning, when I get the implant, will it cancel out the drop shot right away, or does the depo shot stay affective until it’s 3 months are up?

  10. i’m on the birthcontrol pills and i was on antibiotic for 10 days. i had sex with my boyfriend and let him come in me only 3 days after being off the antibiotic what are the chances i am pregnant?

  11. I recently had emergency surgery around a month ago. I was unable to properly shower for 3 days. I received 4 rounds of powerful antibiotics and not enough fluids to push it them through me system. The 1 hour before entering the hospital , my husband and i had intercourse. I fear the implanon wasn’t effective, is there a chance i could be pregnant?

  12. Will I Get Pregnant If I Take Rifampicin and yet am on an implanon…… and after taking the drug will the implanon be effective…..?

  13. I am on depo vera and I am taking Nitrofurantoin (antibiodics) for a bladder infection and I had unprotected sex while taking the medicine , should I be worried about being or getting pregnant on this medicine?

  14. I have the nexplanon and I was prescribed Flagyl and was told that it will interfere with my Birth control and I could end up pregnant, is that true?

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