Can I drink alcohol with Metformin?

How Metformin interacts with alcohol

Metformin is a biguanide that lowers blood glucose by reducing hepatic gluconeogenesis and improving insulin sensitivity. It carries a rare but serious risk of lactic acidosis — a buildup of lactate when oxidative metabolism is impaired. Alcohol impairs lactate clearance by competing for NADH in the liver and by reducing hepatic gluconeogenesis on its own. Binge drinking plus metformin raises lactic acidosis risk significantly, while moderate drinking has not been shown to cause clinically meaningful problems in otherwise healthy patients.

Safety guidance

• Moderate drinking (1 drink/day for women, 2/day for men, with food): generally safe for stable patients with good kidney function (eGFR >45).
• Binge drinking (4+ drinks for women, 5+ for men in a session): avoid with metformin — acute lactic acidosis risk.
• Hypoglycemia: alcohol blunts the liver's glucose-release response; if you're also on sulfonylureas or insulin, alcohol + missed meals can cause severe lows.
• eGFR matters: if your kidney function is below 45 mL/min/1.73m², risk climbs — alcohol should be strictly avoided.

When to avoid alcohol completely

• eGFR below 45 or acute kidney injury
• Active heart failure (NYHA III–IV), severe liver disease
• Any history of lactic acidosis
• Recent dehydration, vomiting, or acute illness
• Fasting or markedly reduced food intake

Clinical sources

• FDA label for metformin (Glucophage) — boxed warning on lactic acidosis and section 5.1.
• ADA Standards of Care in Diabetes 2024 — section on pharmacotherapy and lifestyle.
• EMA SmPC for metformin — section 4.4 "Special warnings."
• Lalau JD et al. "Metformin-associated lactic acidosis." Diabetes Care (PMID: 29773670).