Alcohol Intolerance: Symptoms and Causes

Alcohol Intolerance: Symptoms and Causes

Last Updated: February 15, 2023

Alcohol intolerance can be extremely frustrating to people who like to drink alcohol but can also affect those who do not. This condition causes a reaction to alcohol similar to a hangover but occurs almost immediately when using alcohol. Many people with an alcohol intolerance find themselves unable to drink any alcohol without experiencing the effects this condition causes.

What Is Alcohol Intolerance?

Alcohol intolerance is a medical condition in which your body cannot break alcohol down normally. This results in a build-up of a chemical called acetaldehyde, which is thought to play a large role in causing hangovers. In most people, acetaldehyde is broken down into other chemicals very quickly; however, in people with alcohol intolerance, it builds up and causes the symptoms of alcohol intolerance.

Alcohol intolerance can cause symptoms like flushing in the face, a stuffy nose, and a headache. This condition is normally inherited genetically but can also be caused by certain medications.

Alcohol Allergy vs Intolerance

Alcohol intolerance is different from an alcohol allergy. Alcohol intolerance causes acetaldehyde to build up in your bloodstream, ultimately causing unpleasant symptoms. 

Alcohol allergy, on the other hand, is caused because your body’s immune system attacks a component of an alcoholic beverage. Something in the alcohol, such as hops or grapes causes most alcohol allergies, rather than the alcohol itself. Unlike alcohol intolerance, alcohol allergy varies significantly between individuals, ranging from irritating to deadly.

How Common Is Alcohol Intolerance?

Alcohol intolerance is related to various diseases, like lymphoma, and has been researched by medical scientists; however, there is not much good data on how prevalent alcohol intolerance actually is. Alcohol intolerance is considered a rare disease, meaning it is quite uncommon. Many authorities note that people who believe they have alcohol intolerance often find they actually have an allergy to alcohol.

Symptoms of Alcohol Intolerance

Alcohol intolerance can cause many symptoms and may differ between individuals. Symptoms of alcohol intolerance include: 

  • Stuffy nose
  • Nausea and vomiting
  • Rapid heartbeat
  • Low blood pressure
  • Abdominal pain
  • Headache
  • Fatigue
  • Diarrhea

Additionally, those with asthma may notice a worsening of their asthma symptoms or experience an asthma flare.

When To See A Doctor

The symptoms of alcohol intolerance are unpleasant but rarely dangerous and will eventually go away on their own. However, if asthma symptoms occur with alcohol intolerance, it is good to see your doctor and ensure you are managing your asthma correctly. Otherwise, you should see a doctor if you need help managing other symptoms of alcohol intolerance.

You should also consider seeing a doctor if you may have an alcohol allergy instead of alcohol intolerance or if you are unsure which you have. An allergic reaction can be dangerous, and being evaluated by a doctor may help you avoid a severe allergic reaction.

What Causes Alcohol Intolerance?

Many different things can cause alcohol intolerance. The most common cause of alcohol intolerance is inheriting a gene that affects how alcohol is broken down. This is most common in people of Asian descent but can be present in anyone.

Additionally, certain medications may lead to alcohol intolerance. The antibiotic metronidazole (Flagyl) can cause alcohol intolerance while being used. Another medication called disulfiram (Antabuse) is actually designed to cause alcohol intolerance to help people stop drinking. 

Finally, certain diseases can cause alcohol intolerance. The best-known condition to cause alcohol intolerance is Hodgkin’s lymphoma; however, other conditions may also cause it. Alcohol intolerance is still normally uncommon in people with these types of conditions.

Post-COVID Alcohol Intolerance

There are some anecdotal cases of people experiencing alcohol intolerance after having COVID-19. However, there is no evidence showing that COVID-19 actually causes alcohol intolerance. Even in most anecdotal cases, the inability to drink as much often seemed to be related to fatigue or other symptoms of long-COVID.

COVID-19 is a new disease, and much research is still being done on its long-term effects. While there is no evidence to suggest that the after-effects of COVID are likely to cause alcohol intolerance, new evidence may emerge as research continues.

Can You Develop A Sudden Intolerance to Alcohol?

A sudden intolerance to alcohol is possible if you begin using a medication that causes alcohol intolerance or develop a disease that causes it. Most cases of suddenly developed alcohol intolerance occur due to starting a new medicine that causes it. Genetic alcohol intolerance will not begin suddenly and will be present from birth.

Can You Prevent Alcohol Intolerance?

The genes you inherit cause genetic alcohol intolerance and it cannot be prevented. Alcohol intolerance caused by medications can be prevented by not using the medication that causes it or avoiding drinking while using those medicines. Alcohol intolerance caused by a disease cannot be prevented once the condition is present and requires treating the underlying disease.

How Is Alcohol Intolerance Diagnosed?

Alcohol intolerance caused by genetics is diagnosed through genetic testing. More commonly, however, it is diagnosed solely based on the occuring symptoms and their connections to alcohol. Your doctor may also order an alcohol allergy test to rule out that an allergy is causing the symptoms. If alcohol allergy has been ruled out and the symptoms are connected to alcohol use, alcohol intolerance is often diagnosed without further testing.

Treatment for Alcohol Intolerance

There is no treatment for alcohol intolerance. For people who have alcohol intolerance due to a medication, stopping the medication will help the alcohol intolerance resolve; however, there is no cure for those with alcohol intolerance due to genetics. 

Your doctor can give you medications to lessen the symptoms of alcohol intolerance, such as anti-inflammatory medicines for pain. However, many of these medicines are not supposed to be used with alcohol. Additionally, medications only help mask symptoms and do not help with the underlying problem. Ultimately, the best way to avoid alcohol intolerance is to avoid using alcohol completely.


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