Metformin: What it is and why people take it

Metformin is a first-line oral medicine for type 2 diabetes and prediabetes. It helps lower blood sugar by reducing glucose production in the liver and improving how your body uses insulin. Doctors also prescribe it for polycystic ovary syndrome (PCOS) because it can help with insulin resistance and sometimes improve menstrual cycles.

How to take metformin safely

Start low, go slow. Common starting doses are 500 mg once daily or 500 mg twice daily, then your provider usually increases it over weeks. Typical daily ranges sit between 1,000 and 2,000 mg depending on response and tolerance. If stomach upset is a problem, take metformin with food or switch to the extended‑release (XR) version—XR often cuts down on nausea and diarrhea.

Before you begin, your doctor should check kidney function (eGFR). Metformin is usually avoided if eGFR is under 30 mL/min/1.73 m2 and used with caution below 45. Tell your provider about other conditions—liver problems, heavy alcohol use, or heart failure raise the risk for rare but serious complications.

Common side effects and important warnings

The most common issues are gastrointestinal: nausea, loose stools, abdominal cramping. These often lessen after the first few weeks. If GI problems persist, try splitting the dose, lowering it, or using XR. Routine monitoring for vitamin B12 is wise—long‑term metformin can lower B12 levels and cause numbness or fatigue if untreated.

There’s a very rare risk called lactic acidosis, which is serious. Watch for extreme tiredness, muscle pain, trouble breathing, or stomach pain with vomiting. If those appear, get urgent care. Avoid heavy alcohol while on metformin—alcohol raises lactic acidosis risk and can mess with blood sugar control.

Special situations: some imaging tests that use iodinated contrast or planned surgery may require pausing metformin. Follow the specific instructions your clinic gives. Pregnant people and breastfeeding mothers should discuss metformin with their OB—sometimes it’s continued, sometimes not.

Beyond blood sugar control, metformin can help with modest weight stabilization and has shown favorable effects on long‑term outcomes in some large diabetes studies. It isn’t a miracle weight drug, but many people appreciate this neutral or slightly beneficial effect.

If you’re buying meds online, use licensed pharmacies that ask for a valid prescription, show clear contact info, and are accredited. Avoid sites that sell without prescriptions or offer suspiciously low prices. Keep copies of lab results and share them with any new provider so dosing stays safe.

Practical checklist: get baseline and periodic kidney tests, ask for a B12 check after a year or two, start low and increase slowly, take with food, and always tell any clinician you see that you take metformin. Ask questions—your healthcare team wants you to use it safely and confidently.