How much alcohol you have to drink before it weakens your immune system

• Alcohol does weaken the immune system, when consumed excessively.
• One to two drinks a day is generally considered safe, and likely doesn't weaken the immune system significantly.
• You should refrain from drinking too much alcohol if you don't want to get sick, and you shouldn't drink alcohol if you are sick.

The immune system is how your body defends itself from infections — like harmful bacteria and viruses — and prevents you from getting sick. But just like a muscle, the immune system can become weak and fail to protect you against infection as well.

Healthy habits, such as being active, eating a balanced diet, and getting enough sleep, can keep your immune system strong. But unhealthy factors, like stress, smoking, or drinking alcohol, can be taxing for your immune system and make it harder for it to fight off infection.

Here's what you need to know about how alcohol affects your immune system.

Excessive alcohol use weakens the immune system

According to Mayo Clinic, drinking too much alcohol weakens the immune system and makes you more prone to getting sick. The Centers for Disease Control and Prevention (CDC) defines excessive drinking as:

• Heavy drinking: eight or more drinks a week for women, and 15 or more drinks a week for men
• Binge drinking: four or more drinks in two to three hours for women; five or more drinks in that same time time period for men
• Drinking while pregnant or younger than the legal drinking age of 21

Alcohol alters the makeup of your gut microbiome — home to trillions of microorganisms performing several crucial roles for your health — and affects those microorganisms' ability to support your immune system. It seems that drinking alcohol may also damage the immune cells that line the intestines and serve as the first line of defense against bacteria and viruses.

"By damaging those cells in your intestines, it can make it easier for pathogens to cross into your bloodstream," says Nate Favini, MD, medical lead at Forward, a preventive primary care practice. That is, by drinking too much, you decrease your body's defensive mechanisms to fight off a cold, virus, or other bacterial or viral infections.

And it's not just that you're more likely to get a cold — excessive drinking is linked to pneumonia and other pulmonary diseases. It can also lead to a wide range of health problems, including high blood pressure and heart disease, liver disease, and increased risk of cancer.

"Drinking alcohol in large quantities even just for a short period of time — like binge drinking — can be bad for your health and your immune system," says Favini.

For example, a 2015 study in the journal Alcohol found that binge drinking can reduce infection-fighting white blood cells known as monocytes in the hours after peak intoxication, essentially weakening your immune system.

Moderate alcohol use may not weaken the immune system, but you should be careful

According to Favini, a moderate amount of drinking — one drink per day for women, and two drinks per day for men per the United States Dietary Guidelines for Americans — is generally safe for people in good health and unlikely to have a negative effect on their immune systems.

"Anything above that, regardless of time period, is exposing your body to more alcohol than is ideal," says Favini.

Moreover, some people shouldn't drink at all, according to the Dietary Guidelines. This includes people who are pregnant, have alcohol abuse disorder, or are taking medications that interact with alcohol. Certain conditions also make alcohol problematic, Favini says.

"Anyone with chronic liver conditions should be avoiding alcohol, for example, people with hepatitis, nonalcoholic fatty liver disease, liver inflammation, and any condition that could affect liver function would be a reason to avoid alcohol," notes Favini.

Overall, avoid drinking more than moderate amounts if you want your immune system in good shape, says Favini. And if you feel like you're coming down with something or are sick, do not drink. Not only will drinking alcohol reduce your immune system's strength, but alcohol also has a dehydrating effect.

"When you're feeling run down or like you might get sick, you want to be well hydrated so that all the cells in your body have enough fluid in them and can work really well," Favini says. "You don't want to be dehydrated when you're fighting off an infection."