Metformin, not the pill, lifted mood in women with PCOS

Women with PCOS carry a high risk of depression and anxiety, and the condition's symptoms, from irregular cycles to acne and excess body hair, weigh heavily on quality of life. The two most commonly prescribed treatments, the combined oral contraceptive pill and metformin, are usually chosen for their effects on hormones and metabolism. Surprisingly little data exists on what they do to mental health and sexual function, the outcomes many women care about most. This analysis set out to fill that gap directly.

The researchers ran a secondary analysis of the COMET-PCOS trial, a randomised study in which neither participants nor investigators knew treatment assignments. A total of 240 women aged 21 to 40 with hyperandrogenic PCOS and a BMI of 25 or above were randomised to six months of a combined pill containing 20μg ethinyl estradiol and 0.15 mg desogestrel, extended-release metformin at 2000 mg a day, or both together. Validated questionnaires measured PCOS-specific quality of life, depressive symptoms, state and trait anxiety, sexual function and sexual distress, with analyses limited to women who responded at both baseline and study end.

Quality of life improved across every domain in the combination group of 60 women, in the pill group of 56 except for menstrual health and acne, and in the metformin group of 51 except for body hair and weight. Depressive symptoms and the prevalence of depression improved only with metformin, remaining unchanged in the pill and combination groups. State anxiety improved with metformin and the combination, while trait anxiety improved in all three groups. On sexual function, the pill group scored lower on desire and arousal with no difference in total score, yet sexual distress decreased in both the pill and metformin groups, and no group saw a change in the prevalence of sexual dysfunction.

The authors note that limited data existed on how these widely used therapies affect mental and sexual health in PCOS, so this trial adds genuinely new information rather than confirming old findings. The overall picture is of favourable or neutral effects, with metformin showing an unexpected edge on mood. Open questions remain: the trial enrolled women with elevated BMI, so whether the pattern holds at lower weights is unknown, and six months leaves longer-term effects untested. The analysis was also restricted to women completing both rounds of questionnaires, which can flatter the results.

For women weighing PCOS treatment options, this is a reason to see mood and sexual wellbeing as legitimate parts of the decision, not afterthoughts. The finding that metformin eased depressive symptoms while the pill did not, and that the pill's modest dampening of desire came without added distress or dysfunction, is exactly the kind of detail worth raising in a consultation. None of it argues for or against either drug on its own; it simply gives a clearer picture of the trade-offs each one carries.