Birth Control Pill vs Metformin for PCOS: What the 2023 Guideline Recommends

The combined pill

The guideline says the combined oral contraceptive pill could be used over metformin for managing excess hair in women with irregular cycles ^[1].

A meta-analysis of 19 trials comparing pills found that ethinyl estradiol with cyproterone acetate cut excess hair and testosterone more than conventional pills, but the authors said the then-pending 2023 guideline would not recommend it as a first-line pill because of a higher venous blood-clot risk in the general population; higher and lower estrogen doses did not differ for excess hair ^[2].

Metformin

Metformin alone should be considered in adults with a BMI of 25 or more for weight, insulin resistance, glucose and cholesterol outcomes, and may be considered below a BMI of 25, with limited evidence ^[1]. Metformin could be used over the pill for metabolic indications ^[1].

The guideline says metformin and active lifestyle change have similar efficacy. Stomach side effects are generally dose-dependent and self-limiting; starting low, increasing by 500 mg every 1 to 2 weeks and using extended-release forms may reduce them ^[1]. Metformin may be linked to low vitamin B12, especially with risk factors such as diabetes or a vegan diet, where monitoring should be considered ^[1].

Taking both

For adults with a BMI of 30 or less, combining the pill and metformin offers little extra benefit over either alone ^[1]. Adding metformin to the pill may help most in higher metabolic risk groups, including a BMI over 30, diabetes risk factors or impaired glucose tolerance ^[1]. Where the pill is not suitable, metformin may be considered for irregular cycles ^[1].

Weight-loss medicines

Anti-obesity medicines including liraglutide, semaglutide and orlistat could be considered with active lifestyle change for higher weight in adults, as in the general population, with effective contraception because pregnancy safety data for GLP-1 drugs are lacking ^[1].

Trial data in PCOS specifically are very limited: the review behind the guideline found 11 trials, and only two comparisons could be pooled ^[3]. See our women's GLP-1 hub for the weight-loss trials.

If you want to get pregnant

For women who do not ovulate and have no other fertility factors, letrozole should be the first-line medicine to induce ovulation; its use is off-label in many countries, and it should not be given if there is any chance of an existing pregnancy, though the guideline notes no evidence of more birth defects than with other ovulation drugs ^[1]. Inositol for fertility is considered experimental; see our inositol guide.