Amoxil with the birth control pill
Many women of reproductive age take a combined or progestogen-only oral contraceptive while also using a chronic medication such as Amoxil (Amoxicillin). The combination is generally fine at 250mg, 500mg, 875mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Amoxil can affect contraceptive efficacy
Combined and progestogen-only contraceptives are metabolised through CYP3A4. Strong CYP3A4 inducers (some antiepileptics, rifampicin, St John's Wort) lower contraceptive plasma levels and reduce efficacy. Whether Amoxicillin acts on CYP3A4 determines whether Amoxil affects contraception. Most agents in Antibiotics have no clinically meaningful effect on the pill at 250mg, 500mg, 875mg.
Practical guidance
According to the prescribing information for Amoxicillin, women on hormonal contraception should review Amoxil with the prescribing pharmacist or doctor. Where an interaction is documented, additional barrier contraception or switching to a non-oral method (IUD, implant) for the duration of Amoxil therapy is the standard mitigation.
Frequently asked questions
Will Amoxil make my pill less effective? ▾
Most Antibiotics medications at 250mg, 500mg, 875mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Amoxicillin states whether the interaction is meaningful.
Do I need a backup contraceptive on Amoxil? ▾
Backup contraception is needed only when there is a documented interaction between Amoxil and the contraceptive method. For most users at 250mg, 500mg, 875mg, no backup is required. The pharmacist confirms whether Amoxicillin interacts with hormonal contraception.
More on Amoxil
- With alcoholAmoxil and alcohol — is it safe to drink?
- With foodShould Amoxil be taken with food?
- Side effectsAmoxil side effects: common, rare and warning signs
- Dosage guideAmoxil dosage guide: how much to take and when
- OnsetHow fast does Amoxil start working?
- DurationHow long does Amoxil last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.