Based on NIH | Is it safe to drink alcohol on an empty stomach while taking metformin?

Alcohol on an empty stomach while taking metformin is generally not safe. Alcohol can raise the risk of a rare but serious condition called lactic acidosis with metformin, and drinking without food can further raise the chance of low blood sugar, especially if you also skip meals, exercise hard without eating, or combine metformin with other diabetes medicines. ^{[1] [2]}

Why this matters

• Metformin by itself rarely causes low blood sugar, but hypoglycemia can happen if you do not eat enough or if you drink alcohol. ^{[3] [2]}
• Alcohol is known to intensify metformin’s effect on lactate metabolism, which can increase the risk of lactic acidosis; this risk is higher with excessive (binge or regular heavy) drinking. ^{[4] [1]}
• Labels for metformin advise not to “drink a lot of alcoholic drinks,” including avoiding binge episodes, because it raises lactic acidosis risk. ^{[5] [6]}

Specific risks when drinking on an empty stomach

• Increased hypoglycemia risk: Not eating (caloric deficiency) and drinking alcohol are both listed situations where hypoglycemia can occur with metformin, even though metformin alone usually does not cause it. ^{[2] [3]}
• Additive effects if you use other glucose‑lowering drugs: If metformin is combined with insulin or sulfonylureas, alcohol and an empty stomach can further increase hypoglycemia risk. ^{[7] [2]}
• Lactic acidosis risk: Alcohol potentiates metformin’s impact on lactate handling; product guidance consistently warns against excessive alcohol intake for this reason. ^{[8] [9]}

What “safe” alcohol use looks like with metformin

• Avoid heavy or binge drinking; official guidance explicitly warns not to binge or drink a lot regularly while on metformin because it can increase lactic acidosis risk. ^{[1] [5]}
• If you choose to drink, it is safer to have alcohol with food rather than on an empty stomach to reduce hypoglycemia risk. ^{[2] [3]}
• Extra caution if you are older, malnourished, or have other conditions (e.g., liver issues), as these factors heighten vulnerability to hypoglycemia and lactic acidosis; labels advise avoiding excessive alcohol and exercising caution with hepatic impairment. ^{[2] [9]}

Practical tips if you do drink

• Eat before and during drinking to keep blood sugar more stable, since hypoglycemia is more likely when caloric intake is low. ^{[2] [3]}
• Limit quantity and avoid binges; “do not drink a lot of alcoholic drinks” is the standard instruction with metformin. ^{[1] [6]}
• Be careful with cocktails high in simple sugars; swings in glucose can be harder to predict when combined with metformin and alcohol. ^[2]
• If you also take insulin or a sulfonylurea, consider checking your glucose more frequently when drinking and have a source of fast carbs available. ^{[7] [2]}

Warning signs that need urgent care

• Symptoms suggestive of lactic acidosis: unusual muscle pain, feeling very weak or tired, trouble breathing, stomach pain with nausea or vomiting, dizziness, or feeling cold seek immediate medical attention, as alcohol increases this risk with metformin. ^{[1] [8]}
• Symptoms of hypoglycemia: shakiness, sweating, confusion, dizziness, or palpitations treat promptly with fast-acting carbohydrates and seek care if not improving. ^{[2] [3]}

Bottom line

• With metformin, alcohol should be limited, and you should avoid drinking on an empty stomach to lower the risks of hypoglycemia and lactic acidosis. ^{[1] [2]}
• Do not binge drink or drink heavily while on metformin, as product guidance links this behavior with higher lactic acidosis risk. ^{[5] [6]}