Drug Interaction Between Amoxicillin And Nuvaring

In our latest question and answer, the pharmacist discusses the interaction between amoxicillin and Nuvaring.

Question

I am currently using Nuvaring as a contraceptive. If I had sex on the 3rd of July (and he ejaculated in me) and started taking amoxicillin on the 6th of July, could I be pregnant?

Asked by Amber On Jul 08, 2018

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Jul 09, 2018

There likely is not an interaction between Nuvaring, a vaginal contraceptive, and amoxicillin, an antibiotic. Although there is some controversy regarding whether or not antibiotics reduce the efficacy of oral birth control pills, it isn't thought to be a concern with Nuvaring as the hormones from Nuvaring are absorbed vaginally, and bypass the GI tract/liver.


We wrote another article discussing Nuvaring with amoxicillin, which can be found here: Does Amoxicillin Cause Nuvaring Not To Work? Below are some of the important points discussed:

  • Only a few antibiotics are definitively known to cause a decrease in hormone concentrations from birth control pills. One example is the rifamycin family of antibiotics (e.g. rifampin).
  • Rifamycin antibiotics increase metabolism of estrogen by increasing how quickly the liver metabolizes it.
  • Most other antibiotics do not increase metabolism of estrogen in the liver, including amoxicillin.
  • Non-rifamycin antibiotics are thought to potentially affect the hormones from birth control pills by reducing bacteria in the GI tract, which are partially responsible for metabolism of estrogen.
  • However, little conclusive evidence exists that hormone concentrations are significantly affected in those taking antibiotics.
  • Nevertheless, some studies have shown that a small number of individuals may experience significant decreases in hormones when taking antibiotics and therefore back-up contraception is recommended, just to be safe.
  • When it comes to Nuvaring, multiple studies have reported that antibiotics do not reduce hormone concentrations, since the hormones are absorbed vaginally, and not in the GI tract.
  • While it doesn't appear antibiotics interfere with Nuvaring, more data is needed to put forth a firm conclusion. As unplanned pregnancy has major consequences, it may be prudent to use an additional method of birth control during short-term antibiotic use with Nuvaring, just to be safe.​​​


In your situation, being on Nuvaring and starting antibiotics 3 days after intercourse should not cause any issues.

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of PharmacistAnswers.com. He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Brian.Staiger@PharmacistAnswers.com Office: 716-389-3076

About Amoxicillin

Amoxicillin is an semisynthetic "aminopenicillin" similar to ampicillin and penicillin. It does however, have a broader spectrum of antibacterial effects than penicillin and is better absorbed than ampicillin. Amoxicillin is used to treat a variety of infections including: Otitis media, bronchitis, sinusitis, and bacterial cystitis. In general, amoxicillin can be given with or without food but food may reduce any gastrointestinal side effects.

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