Metforminميتفورمين

Metformin, sold under the brand name Glucophage, is one of the most widely used medicines for type 2 diabetes, taken by mouth alongside diet and exercise.

Metformin lowers blood sugar through three actions:

• Reducing the amount of sugar absorbed from the intestine
• Decreasing the amount of sugar produced by the liver
• Improving the body's response to its own insulin

• Blood sugar control in type 2 diabetes, alone or combined with other diabetes medicines or insulin
• Blood sugar control in gestational diabetes
• Sometimes used to help prevent type 2 diabetes in people with prediabetes
• Sometimes used for polycystic ovary syndrome (PCOS)
• Sometimes used to help manage weight gain caused by antipsychotic medicines

Standard tablets, adults

• Starting dose: 500 mg twice daily, or 850 mg once daily, taken with meals
• The dose is increased gradually — typically by about 500 mg a week, or 850 mg every two weeks — based on blood sugar response and tolerance
• Maximum dose: approximately 2,250–2,550 mg per day; doses above 2,000 mg a day are usually better tolerated split into three doses

Extended-release tablets, adults

• Starting dose: 500–1,000 mg once daily with the evening meal
• Increased gradually, typically by about 500 mg a week
• Maximum dose: approximately 2,000–2,500 mg per day

Children (10 years and older), type 2 diabetes

• Starting dose: 500 mg twice daily, with meals
• Maximum dose: up to about 2,000 mg per day

PCOS

• Typically 1,500–2,500 mg per day, in divided doses

This is educational background, not an individual prescription — your own doctor sets your exact dose and titration schedule.

• Take with food to reduce nausea
• Take at approximately the same time each day
• Swallow extended-release tablets whole — do not chew or crush them
• If using the oral suspension, shake it well and measure the dose with the device provided, not a household spoon

Take the missed dose as soon as remembered, unless it is almost time for the next dose — in that case, skip the missed dose and resume the normal schedule. Do not take a double dose.

• Store at room temperature
• Keep away from light, direct sunlight, and moisture

• Diarrhea — very common with standard tablets (reported in roughly half of users in some data), less common with extended-release tablets (roughly 10–13%)
• Nausea and vomiting — vomiting reported in up to about a quarter of users in some data
• Bloating and gas — bloating reported in roughly 12%
• Indigestion — reported in roughly 7%
• Reduced vitamin B12 absorption over time — reported in roughly 7–17% with long-term use
• Weakness — reported in roughly 9%
• Headache — reported in roughly 6%
• Stomach pain or burning
• Constipation
• Metallic taste in the mouth
• Cold-like symptoms (sore throat, stuffy nose)

Metformin carries a boxed warning for lactic acidosis, a rare but serious and potentially life-threatening buildup of lactic acid in the blood. Deaths, dangerously low body temperature, and low blood pressure have been reported. Onset can be subtle, with vague symptoms such as:

• General malaise
• Muscle pain
• Difficulty breathing
• Unusual drowsiness
• Abdominal pain

Risk is higher with kidney or liver problems, age 65 and older, dehydration, infection, excess alcohol use, and around surgery or contrast-dye imaging procedures. Seek medical attention immediately if these symptoms occur — lactic acidosis requires stopping the medicine right away and hospital treatment, sometimes including dialysis.

• Known hypersensitivity to metformin
• Acute or chronic metabolic acidosis, including diabetic ketoacidosis
• Severe kidney impairment (eGFR below 30 mL/min/1.73m²)
• Chronic heart failure requiring drug treatment (discuss with your doctor)

Increased low-blood-sugar risk

• Insulin and other diabetes medicines — combining them with metformin increases the risk of hypoglycemia; dose adjustment may be needed

Other noted interactions

• Diuretics such as furosemide
• Certain glaucoma medicines (zonisamide, acetazolamide) and methimazole
• Some heart and blood-pressure medicines
• Hormonal therapies (testosterone, estrogen, progesterone)
• Nicotinic acid
• Certain seizure medicines (topiramate, phenytoin)
• Certain antipsychotics (phenothiazines, fluphenazine)
• Pacritinib, ranolazine, risdiplam, selegiline

Imaging with contrast dye

• Metformin should be stopped at the time of an iodinated contrast-dye procedure in people with reduced kidney function or a history of liver disease, alcohol misuse, or heart failure, and kidney function is rechecked about 48 hours afterward

Always tell your doctor and pharmacist about every other medicine you take.

Metformin is generally considered one of the safer diabetes medicines to use during pregnancy, though insulin is often preferred and a doctor's guidance is needed either way.

For breastfeeding, metformin passes into breast milk in small amounts — discuss with your doctor before use.

• Vitamin B12 levels — your doctor may recommend periodic checks or supplementation during long-term use
• Kidney function — checked periodically, and especially before and after contrast-dye imaging
• Avoid alcohol, or use only in moderation — it can lower blood sugar further and raises the risk of lactic acidosis
• Use with caution in liver disease, cardiovascular disease, severe dehydration, or acute infection
• Elderly patients usually start at the lower end of the dose range