Metformin is a prescription medicine that lowers the glucose your liver makes and improves insulin sensitivity.
What metformin is
Metformin was originally a type 2 diabetes drug. It works by reducing the amount of glucose the liver releases into the blood and by helping the body’s cells respond better to insulin. For that reason it belongs to the group of medicines that improve insulin sensitivity rather than ones that add more insulin. Metformin is taken by mouth and comes in standard and slow-release forms, with the choice made by a doctor.
Why it is linked to PCOS
Many women with PCOS have insulin resistance, where the body becomes less responsive to insulin. This can contribute to hormonal imbalance and irregular menstrual cycles. Because of this link, doctors sometimes prescribe metformin to help with blood-glucose control and, in some women, to improve cycle regularity and ovulation. However, metformin targets a metabolic driver rather than curing PCOS. It is also not suitable for everyone with the condition, and the effect varies from person to person.
Key points about safety
Metformin is a prescription-only medicine. This means it should only be started, adjusted, or stopped on a doctor’s advice, and it should never be self-started even if it seems easy to obtain. Common side effects include nausea, diarrhoea, and bloating, especially early on, and these often ease when the medicine is taken with food. Long-term use can lower vitamin B12 levels, so a doctor may monitor this over time. Any other medicines, kidney conditions, or pregnancy should also be discussed, as they affect whether this medicine is appropriate.
What it means for you
If you have PCOS symptoms such as irregular periods or signs of insulin resistance, metformin may be one option that gets discussed, but it is not a stand-alone fix. It is often used alongside lifestyle changes such as nutrition and physical activity, and its full effect can take several weeks to judge. Some women notice a benefit in their cycles, while others respond less, so a doctor often reviews progress over time. It is also worth remembering that stopping it suddenly can undo the control that has been achieved. The decision to start, continue, or stop it, including dose and duration, should be made with a doctor or pharmacist who reviews your overall health, rather than from online information alone.
This glossary is education, not diagnosis. For your own situation, ask a doctor or pharmacist.