Glucophage 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 Glucophage (Metformin). The combination is generally fine at 500mg, 850mg, 1000mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Glucophage 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 Metformin acts on CYP3A4 determines whether Glucophage affects contraception. Most agents in Diabetes Treatment have no clinically meaningful effect on the pill at 500mg, 850mg, 1000mg.
Practical guidance
According to the prescribing information for Metformin, women on hormonal contraception should review Glucophage 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 Glucophage therapy is the standard mitigation.
Frequently asked questions
Will Glucophage make my pill less effective? ▾
Most Diabetes Treatment medications at 500mg, 850mg, 1000mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Metformin states whether the interaction is meaningful.
Do I need a backup contraceptive on Glucophage? ▾
Backup contraception is needed only when there is a documented interaction between Glucophage and the contraceptive method. For most users at 500mg, 850mg, 1000mg, no backup is required. The pharmacist confirms whether Metformin interacts with hormonal contraception.
More on Glucophage
- With alcoholGlucophage and alcohol — is it safe to drink?
- With foodShould Glucophage be taken with food?
- Side effectsGlucophage side effects: common, rare and warning signs
- Dosage guideGlucophage dosage guide: how much to take and when
- OnsetHow fast does Glucophage start working?
- DurationHow long does Glucophage last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.