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Does the antibiotic Augmentin lower the effectiveness of pills? #1125/9
HI, I was wondering if the antibiotic Augmentin, decreases the effectiveness of the birth control pill. Should a back-up method be used?

Thank you

The antibiotic Augmentin does not lower the effectiveness of pills.


Here is lots more:

The drugs that do and do not decrease the effectiveness of hormonal contraceptives are listed below:

Drugs that decrease pill effectiveness by increasing liver hormone  breakdown:
Carbamazepine (Tegretol), Nevirapine, Oxcarbazepine (Trileptal), > Phenobarbital, Phenytoin (Dilantin), Primidone (Mysoline), Rimidone (Mysoline), Rifabutin, Rifampicin, St. John's Wort,
Topiramate (Topamax), Lamotrigine (Lamictal)*
 *Lamictal is, itself affected by pills and pills affect Lamictal (more to follow- P52-Policar)

Drugs that do not cause induction of liver enzymes:
Sodium Valproate (Depakote, Depakene), Clonazepire, Ampicillin, Clarithromycin, Metronidazole,
Ciproflaxacin, Ofloxacin, Doxycycline, Fluconazole, Ethosuximide (Zarontin), Levetiracetam (Keppra), Vigabatrin (Sabril), Zonigamite (Zonegram), Pregabalin (Lyrica), Clonazepam (Klonopin), Tigabine (Gabitril)

Possibly ethosuximide, griseofulvin, troglitazone, Vigabatrin and Provigil (modafinal) [Speroff, Darney; A Clinical Guide for Contraception.  Fourth edition 2005, page 101] [Guillebaud, Contraception: Your Questions Answered; Fourth edition, Pages 123-130] [Physicians Desk Reference 2007: p.990]

Broad-spectrum antibiotics:
"Broad-spectrum antibiotics such as amoxicillin and tetracycline, which alter the intestinal flora thought to be instrumental in promoting absorption of the sex steroids, do not reduce the efficacy of OC's.  Women using the antibiotics do have statistically significant but not clinically lower serum levels of estrogen and progestins.  However, virtually every woman taking these antibiotics has remained well within the therapeutic range for the sex steroids.  168-170[Murphy 1991] [Neely 1991] [Friedman
1980].  As a result, back-up methods should not be necessary unless the patient has problems taking her pills, e.g., if her underlying medical condition interferes with pill taking or absorption.  Long-term use of
broad-spectrum antibiotics (such as erythromycin or tetracycline for acne) is compatible with OC use; back-up methods are not routinely needed for pregnancy prevention. 171[Helms 1997].

Given all the conflicting messages, here is an attempt at summarizing, but not cutting through, the confusion regarding the antibiotics most women and their health care providers are most concerned about:

If you are taking a broad spectrum antibiotic such as tetracycline, doxycycline, ampicillin or erythromycin, some clinicians recommend that you use a back-up contraceptive, others do not. Some women taking these broad spectrum antibiotics use a back-up contraceptive, others do not. The
decision is up to you.

Here are the words of advice from the Planned Parenthood Federation of America: "There is no pharmacologic evidence that the acute or chronic use of systemic antibiotics (e.g. tetracycline, ampicillin) decreases the efficiency of low-dose COCs in women who take them correctly."


Michael Policar, MD, MPH

Associate Clinical Professor of Obstetrics, Gynecology and Reproductive Sciences

University of California, San Francisco


Key Words:  antibiotic, Augmentin, effectiveness, birth control pills, back-up methods, decrease, liver hormone breakdown, Planned Parenthood Federation of America, combined oral contraceptives


Robert A. Hatcher MD, MPH
Emeritus Professor of Gynecology and Obstetrics
Emory University School of Medicine
Atlanta, GA

The directors and owners of this website and any publications and information concerning health matters offered here advise a person with a particular problem to consult a primary-care clinician or a specialist in obstetrics, gynecology, or urology (depending on the problem or the contraceptive) as well as the product package insert and other references before diagnosing, managing, or treating the problem.
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