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Medically Verified MonographPrescriptionClass: Biguanides

Metformin

Generic Name: Metformin Hydrochloride

Common Brand Names: Glucophage, Fortamet, Glumetza, Riomet
Dosage Form:Tablet, Oral Solution
Route:Oral
Pregnancy Category:B
Last Reviewed:9/6/2026

Seek Urgent Medical Attention If:

Symptoms of Lactic Acidosis: Severe malaise, rapid deep breathing (Kussmaul breathing), severe somnolence, cold clammy extremities.

Uses & Medical Indications

Improve glycemic control in adults and children with type 2 diabetes mellitus

Medical Conditions Treated:

Type 2 Diabetes Mellitus, Polycystic Ovary Syndrome (Off-label)

Dosage & Administration Guidelines

Adult Dosage

500 mg orally twice a day or 850 mg orally once a day initially

Pediatric Dosage

500 mg orally twice a day (children 10-16 years)

Elderly / Geriatric Considerations

Consider lower initial dose due to potential renal function decline

Maximum Dose Limit

2550 mg/day (adults), 2000 mg/day (pediatrics)

Renal Impairment:

Contraindicated if eGFR < 30 mL/min/1.73 m2. Dose adjustment required for eGFR 30-45.

Hepatic Impairment:

Avoid use in patients with clinical or laboratory evidence of hepatic disease.

Side Effects & Safety Warnings

Common Side Effects

Diarrhea, nausea, vomiting, flatulence, asthenia, indigestion, abdominal discomfort

Serious Adverse Reactions

Lactic acidosis, Vitamin B12 deficiency, Hypoglycemia (when used with other antidiabetics)

Contraindications:

Severe renal impairment, acute or chronic metabolic acidosis (including diabetic ketoacidosis)

Important Warnings & Precautions:

Risk of lactic acidosis, especially in renal impairment, older age, or use of contrast dye.

Interactions (Drugs, Food & Alcohol)

Drug-Drug Interactions:

Carbonic anhydrase inhibitors, drugs that reduce metformin clearance (e.g., ranolazine, dolutegravir)

Food & Dietary Interactions:

Take with meals to reduce gastrointestinal side effects.

Alcohol Interaction Warning:

Avoid excessive alcohol intake as it increases the risk of lactic acidosis.

Identified Clinical Drug Interactions for Metformin:

Metformin + Iodinated RadiocontrastMajor Interaction

Increased risk of contrast-induced nephropathy leading to severe Metformin-associated Lactic Acidosis (MALA).

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Pregnancy & Breastfeeding Safety

Pregnancy Safety

May be used during pregnancy if needed, but insulin is often preferred.

Breastfeeding / Lactation

Present in human milk. Benefits must be weighed against potential risks to infant.

Patient Counseling & Practical Advice

How to Take:

Take with meals. Report symptoms of lactic acidosis immediately. Do not skip meals.

What to Do if You Miss a Dose:

Take as soon as remembered. If it is almost time for the next dose, skip the missed dose. Do not double up.

Recommended Monitoring & Lab Tests:

Renal function (eGFR), HbA1c, fasting blood glucose, hematologic parameters (annually)

Frequently Asked Questions

Trustworthy Sources & Medical Review

Content for Metformin was synthesized and fact-checked against standardized regulatory monographs, official pharmacopoeias, and national health authorities:

  • American Diabetes Association (ADA)Standards of Medical Care in Diabetes - Pharmacologic Approaches
  • European Association for the Study of Diabetes (EASD)Consensus Guidelines on Metformin Therapy
Reviewer Credentials: PharmD, Clinical PharmacologistLast Reviewed Date: 9/6/2026

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