Metformin and alcohol: can you drink while taking metformin?

Metformin is one of the most popular prescription drugs, with over 92 million active prescriptions in the United States alone (as of 2020).

It is used to help people with prediabetes and type 2 diabetes better manage their blood sugar levels and helps both in managing insulin resistance and in maintaining and losing weight.

However, there are many questions about taking metformin and incorporating it into your daily life, such as what to eat and what not to eat while taking the medicine and whether or not you can (and should?) drink alcohol while taking the medicine.

In this article, we will explore everything you need to know about drinking alcohol while taking metformin.

What is metformin?

Metformin is often sold under the brand names Glucophage, Glumetza, Glucophage XR, Riomet or Fortamet.

Metformin lowers blood sugar by stopping the liver from producing glucose, and it also increases insulin sensitivity by preventing the body from absorbing all the glucose from food.

It can be taken once or twice a day, usually with lunch. It is an extremely safe drug that is usually well tolerated with minimal side effects.


What are the side effects of metformin? 
Most of the side effects people experience when taking metformin are mild and include: 

Nausea
Stomachache 
Stomach cramps
Vomiting 
Diarrhea 
Loss of appetite
Weight loss 


Some patients gain weight, but this is rare 
Low blood sugar

You can find out more about the potential side effects of metformin in our guide: Metformin side effects: what you need to know.

What happens if you drink alcohol while taking metformin? 
Low blood sugar 
Drinking alcohol can cause a rapid drop in blood sugar in people with diabetes, and taking metformin can also lower blood sugar, so the combination of the two increases the risk of hypoglycemia. 
This can be dangerous as the symptoms of intoxication are similar to those of low blood sugar, so be careful when drinking and monitor your blood sugar closely. 
Symptoms of low blood sugar include:

Trembling
Somnolence 
Confusion
Dizziness
Headache 

Lactic acidosis 
Taking metformin and drinking alcohol can also cause a rare but serious complication called lactic acidosis, which will require immediate medical attention. 
Lactic acidosis occurs when the production of lactic acid exceeds its clearance in the body.  The increase in lactate production is usually due to impaired tissue oxygenation, either due to reduced oxygen delivery to the body or a defect in its use. 
This can happen because metformin causes the body to produce more lactic acid, and alcohol prevents the body from getting rid of the lactic acid as quickly as usual. 
Symptoms of lactic acidosis include:

Stomachache
Decreased appetite
Shallow breathing
Fast heart rate 
Diarrhea
Muscle cramps
Tiredness
Weakness
Somnolence 

If lactic acidosis is not treated promptly, it can lead to damage to the blood vessels, heart, lungs and even kidneys, which can be very damaging to someone already with diabetes. 
If the condition is not treated at all, it will lead to organ failure and death. 

Should you drink alcohol at all if you’re on metformin? 
Alcohol can negatively interact with many different drugs and medications, so it’s always best to talk to your doctor before drinking alcohol if you’ve recently started a new drug or prescription drug. 
Follow all guidelines and instructions for any prescription drugs and follow them. 
However, many people drink alcohol while taking metformin.  As with everything, if you live with diabetes, moderation is always the key. 
The general guidelines are as follows: for women, a moderate amount of alcohol is no more than one drink per day, and for men, a moderate amount is no more than two drinks per day. 

How to make drinking safer if you have diabetes 
There are additional guidelines for drinking alcohol if you have diabetes to make sure you drink in a safer way: 

Don’t drink alcohol when your blood sugar is low
Don’t drink alcohol on an empty stomach (eating a snack containing fat and protein before drinking can help stabilize blood sugar levels)
The pace of drinking water so as not to become dehydrated 
Always carry low blood sugar snacks with you 
Have a snack after drinking
Test your blood sugar before, during and after drinking, especially before going to bed
Wear a continuous glucose monitor (CGM) to better track your blood sugar while drinking, with low-level alarms turned on 
Stay with people who know you have diabetes and know how to treat low blood sugar (and even administer glucagon if needed)
Wear a medical ID bracelet in case of emergency 
Always let someone know where you are going and when you expect to return, along with a way to contact you 
Always keep your cell phone nearby with the ringer on 


Application
Many people with diabetes take metformin for better blood sugar levels, and many people with diabetes taking metformin are also curious to see if they can enjoy alcohol or if there are any negative side effects of combining alcohol and metformin. 
While patients should always heed their doctor’s advice, there are a few dangers of combining alcohol and metformin that you should be aware of. 
The risk of both lactic acidosis and low blood sugar is increased when metformin and alcohol are used together.  In serious cases, these conditions will require immediate medical attention and may be life threatening. 
The symptoms of lactic acidosis, low blood sugar, and drunkenness can be similar, so it’s best to pay attention to your surroundings and drink wisely, if at all. 
Moderation is key for anyone with diabetes who wants to drink alcohol.  Moderate drinking for women is no more than one drink a day, and moderate drinking for men is no more than two drinks a day.  
People with diabetes should never drink alcohol on an empty stomach (snack on protein and fat beforehand to help stabilize low blood sugar) or when blood sugar is low.  They should be with people who know how to treat low blood sugar and have low sugar snacks with them at all times. 
Wearing a CGM (with low alerts on) can help you better monitor your blood sugar while drinking, and checking your blood sugar levels before, during, and after drinking can help prevent low blood sugar. 
It’s important to remember that drinking can cause low blood sugar up to 24 hours later, so be extra vigilant if you choose to drink alcohol and develop diabetes. 
As always, ask your doctor if you have any concerns or questions about drinking alcohol and taking metformin to treat diabetes.