Alcohol Intolerance: Symptoms, Causes and Testing

Written by Theresa Valenzky

& Medically Reviewed by Benjamin Caleb Williams, RN

Medically Reviewed

Up to Date

This article was reviewed by a medical professional to guarantee the delivery of accurate and up-to- date information. View our research policy.

Editorial Policy

Last Updated - 9/15/2023

View our editorial policy
If you or a loved one is struggling with addiction, help is available. Speak with a Recovery Advocate by calling (614) 362-1686 now.

Updated 09/15/2023

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, like 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 that prevents your body from breaking down alcohol normally. The condition leads to a build-up of the chemical acetaldehyde, which can cause unpleasant symptoms like flushing, headache, nausea and vomiting. Alcohol intolerance is most common in people of Asian descent but can occur in anyone.

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 greatly between people, ranging from irritating to deadly.

How Common Is Alcohol Intolerance?

Alcohol intolerance is related to several diseases, like lymphoma, and has been researched by medical scientists; however, there is not much good data on how prevalent alcohol intolerance 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 people. While there is some variation, most of these symptoms will be similar for everyone. Most alcohol intolerance symptoms occur immediately; however, some can be delayed.

Immediate Symptoms

The immediate symptoms of alcohol intolerance will occur right after drinking alcohol. They will typically happen rapidly enough that there is no question as to if it was the alcohol that caused it or not.


One of the primary symptoms of alcohol intolerance is facial flushing. Your face will quickly develop a red coloration as if you blushed. The color change will generally be quite noticeable and affect your entire face. You may notice a feeling of warmth in the skin of your face as the blood flow increases.


The rapid onset of a headache will coincide with the other symptoms. This headache can be throbbing or migraine-like; however, it may also manifest in other ways. This headache will occur immediately and will be different from a headache caused by a hangover or dehydration.

Nausea and Vomiting

Nausea and vomiting are common with alcohol intolerance. This is typically more than just feeling queasy, but severe abdominal cramping and retching that occurs very soon after drinking alcohol. This nausea and vomiting will differ from vomiting that can happen when drinking in that it will be very soon after drinking, occurring suddenly and intensely. 

Rapid Heartbeat

Accompanying the symptoms of alcohol intolerance will be a rapid heartbeat. This may not be noticeable unless you actually feel your pulse; however, some people can feel their heart beating faster. This rapid heartbeat is not typically dangerous unless an underlying health condition exists.

Nasal Congestion

Nasal stuffiness and congestion are almost always present in those with alcohol intolerance. This starts suddenly right after drinking when related to alcohol intolerance. It is important to note that nasal congestion can also be part of an allergic reaction.

Delayed Symptoms

When doctors diagnose alcohol intolerance, they typically use the immediate symptoms it causes. These symptoms are almost always present with alcohol intolerance. There are, however, other symptoms that may occur as delayed symptoms of alcohol intolerance. Unlike the immediate symptoms, these symptoms may or may not happen when alcohol is used.


The acetaldehyde that builds up and causes alcohol intolerance is a major contributing factor in hangovers. While hangovers are often not exclusively due to high acetaldehyde levels, they play a large role. Someone who has alcohol intolerance is more likely to have a hangover, and hangovers that do occur will be more severe than they would have been otherwise.

Alcohol-Related Asthma

Alcohol intolerance increases the severity of asthma if the person with the intolerance already has asthma. There is no evidence to suggest that it causes asthma in those without it; however, it can worsen asthma if already present. This effect may be immediate but can also be a delayed symptom.

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 manage 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.

Genetic Causes

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.

ALDH2 Deficiency

ALDH2 deficiency is a common cause of alcohol intolerance. This genetic deficiency results in decreased levels of aldehyde dehydrogenase, the enzyme that breaks acetaldehyde into non-toxic chemicals. Those with normal aldehyde dehydrogenase levels break acetaldehyde down almost instantaneously, while those with ALDH2 deficiency metabolize it quite slowly.

ADH Enzyme Variants

ADH enzyme variants are genetic changes that alter aldehyde dehydrogenase. This may impair its ability to function normally but means it is still present at normal levels. The effect depends on how much the enzyme is affected. Some people with ADH enzyme variants may not even notice any symptoms, while others will have the same symptoms they would have with ALDH2 deficiency.

Medications and Interactions

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

Disease-Induced Alcohol Intolerance

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 long-COVID symptoms.

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 always be present from birth.

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 occurring 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.

Is There a Cure for Alcohol Intolerance?

There is no cure or treatment for alcohol intolerance unless it is due to medication use or a medical condition. For people who have alcohol intolerance due to a medication, stopping the medication will likely resolve the alcohol intolerance. If it is an inherited genetic condition, medical professionals are limited to providing ways to reduce the unpleasant symptoms of alcohol intolerance. 

Your doctor can give you medications to lessen the symptoms of alcohol intolerance, such as anti-inflammatory medicines for pain. However, many medicines are not supposed to be used with alcohol. Additionally, medications only help mask symptoms and do not help with the underlying problem. High acetaldehyde levels increase your risk of cancer, making it best to avoid using alcohol completely if you have alcohol intolerance.

Can You Prevent Alcohol Intolerance?

The genes you inherit cause genetic alcohol intolerance, which 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.

Avoiding Alcohol

Avoiding alcohol is always the best option for those with alcohol intolerance, as the increased acetaldehyde levels increase your cancer risk. Avoiding alcohol also helps you to avoid the unpleasant symptoms that alcohol intolerance can create.

It is important to remember that for someone with alcohol intolerance, avoiding alcohol is more than just not drinking alcoholic beverages. Alcohol in cough syrups or some kombucha could trigger alcohol intolerance. Some people may be sensitive enough that even alcohol-based hand sanitizers can trigger their alcohol intolerance. Avoiding alcohol includes being aware of any potential exposure to alcohol.

Moderating Your Drinking

If you have alcohol intolerance and are not going to stop drinking, the less alcohol you use, the better your alcohol intolerance will be. Because it is caused by your body’s inability to process alcohol correctly, drinking slowly and giving yourself time between each drink can lessen its severity. Drinking when you have alcohol intolerance does increase your risk of cancer, and you should consider trying to completely stop drinking alcohol instead of just moderating it.

Taking Antihistamines

Antihistamines can help to reduce the intensity and severity of the symptoms alcohol intolerance causes. While this over-the-counter option can make you feel better, it is not actually treating the underlying problem but just masking it. It is far better to avoid alcohol altogether if you have alcohol intolerance instead of solely treating the symptoms.

Support for Alcohol Intolerance

While addiction treatment centers like The Recovery Village Columbus can’t treat alcohol intolerance itself, we can help you stop using alcohol and avoid the negative consequences that alcohol intolerance can bring. If you have alcohol intolerance, it is important to try to stop using alcohol as soon as possible.
We have extensive experience helping those addicted to alcohol gain

View Sources

National Institute on Alcohol Abuse and Alcoholism. “Alcohol and Nutrition.” Alcohol Alert, October 1993. Accessed July 27, 2022.

Mahboub, N., et al. “Nutritional status and eating habits of […] a narrative review.” Nutrition Reviews, June 2021. Accessed May 22, 2022.

Saitz, Richard. “Introduction to Alcohol Withdrawal.” Alcohol Health and Research World, 1998. Accessed July 28, 2022.

Cleveland Clinic. “Does What You Eat Affect Your Mood?” January 12, 2021. Accessed July 27, 2022.

U.S. National Library of Medicine. “Substance use recovery and diet.” MedlinePlus, January 12, 2022. Accessed July 27, 2022.

Salz, Alyssa. “Substance Abuse and Nutrition.” Today’s Dietitian, December 2014. Accessed May 22, 2022.

Harrar, Sari. “Omega-3 Fatty Acids and Mood Disorders.” Today’s Dietitian, January 2012. Accessed May 22, 2022.

Johns Hopkins Medicine. ‘“9 Reasons Why (the Right Amount of) Coffee Is Good for You.” Accessed May 22, 2022.


Get your life back

Recovery is possible. Begin your journey today

Call Us Now Admissions Check Insurance

What To Expect

When you call our team, you will speak to a Recovery Advocate who will answer any questions and perform a pre-assessment to determine your eligibility for treatment. If eligible, we will create a treatment plan tailored to your specific needs. If The Recovery Village is not the right fit for you or your loved one, we will help refer you to a facility that is. All calls are 100% free and confidential.

All calls are 100% free and confidential.