How long should a female patient of reproductive age use a barrier method for birth control while taking Augmentin (amoxicillin/clavulanate) for a bacterial infection?

Barrier Contraception Duration with Augmentin

You do not need to use barrier contraception when taking Augmentin (amoxicillin/clavulanate), as this antibiotic does not reduce the effectiveness of hormonal birth control.

Evidence-Based Rationale

The concern about antibiotics reducing contraceptive efficacy stems from specific drug interactions, but Augmentin is not among the problematic agents:

Antibiotics That DO Require Barrier Methods

Only rifamycins (rifampin, rifabutin, rifapentine) require backup contraception when used with hormonal contraceptives 1. For these medications:

• Women should add a barrier method for the entire duration of rifamycin therapy 1
• This recommendation applies specifically to rifamycins used for tuberculosis treatment 1

Augmentin and Hormonal Contraceptives

Augmentin does not appear in any guideline as requiring contraceptive backup 1. The evidence shows:

• Broad-spectrum antibiotics like amoxicillin/clavulanate have no clinically significant interaction with oral contraceptives in the vast majority of women 2
• The theoretical risk of interference with enterohepatic recirculation affects only approximately 1% of women, and even this subset cannot be reliably identified 2
• No prospective studies demonstrate increased contraceptive failure rates with non-rifamycin antibiotics in compliant oral contraceptive users 2

Clinical Recommendations

For standard practice:

• Continue hormonal contraceptives as usual during Augmentin therapy 2
• No backup barrier method is required 2
• No extension of protection is needed after completing the antibiotic course 2

For the exceptionally cautious patient or those with prior breakthrough bleeding during antibiotic use:

• Consider barrier methods during the antibiotic course plus 7 days after completion 2
• This represents an abundance of caution rather than evidence-based necessity 2

Important Caveats

If vomiting or severe diarrhea occurs within 3 hours of taking a contraceptive pill (whether from Augmentin side effects or any cause):

• Take another pill as soon as possible 1
• Use backup contraception until 2 days after symptoms resolve 1
• Consider emergency contraception if unprotected intercourse occurred 1

The gastrointestinal side effects, not the antibiotic itself, create the contraceptive risk 1.