Combined Oral Contraceptives and Metformin Use

Safety and Efficacy

• The Centers for Disease Control and Prevention (CDC) recommends that patients can safely take combined oral contraceptives (COCs) and metformin at the same time, as there is no pharmacokinetic interaction between these medications that would compromise contraceptive efficacy or patient safety 1, 2
• Metformin is not listed among medications that interact with COCs in the CDC's U.S. Medical Eligibility Criteria for Contraceptive Use, which comprehensively catalogs drug interactions affecting hormonal contraceptives 1, 2
• The American Academy of Pediatrics recommends that when prescribing COCs with metformin, a low-dose formulation containing 30-35 μg ethinyl estradiol with levonorgestrel or norgestimate should be selected 4

Contraceptive Effectiveness

• Broad-spectrum antibiotics, antifungals, and antiparasitics do not affect COC effectiveness, with the exception of rifampin and griseofulvin 1, 3
• The only medications documented to reduce COC effectiveness are enzyme-inducing anticonvulsants, lamotrigine, certain antiretrovirals, and rifampin/rifabutin 1, 2

Patient Guidance

• Patients should still use backup contraception for the first 7 days after initiating COCs to ensure contraceptive efficacy, as recommended by the American Academy of Pediatrics 4, 6
• If the patient is taking other medications concurrently, verify that none are enzyme-inducing agents that could compromise COC effectiveness, particularly anticonvulsants or certain antiretrovirals, as recommended by the CDC 1, 2