Alcohol Intolerance

Overview

Alcohol intolerance is a condition in which the body cannot fully break down alcohol, leading to uncomfortable symptoms that appear immediately or very shortly after drinking. Although it may resemble an allergy, alcohol intolerance develops through a different mechanism. It is the digestive system and metabolism that are involved, not the immune system.

Normally, alcohol is broken down in the liver in two stages. It is first converted into a toxic substance called acetaldehyde, which is then broken down into acetate and cleared from the body. In alcohol intolerance, this second step does not occur adequately. Acetaldehyde builds up in the blood and causes symptoms such as facial flushing, nausea, and a rapid heartbeat.

Alcohol intolerance most commonly stems from an inherited enzyme deficiency. Particularly common in people of East Asian descent, it develops when an enzyme called aldehyde dehydrogenase 2 (ALDH2) does not function adequately. Alcohol intolerance is not purely a genetic condition, however. Certain medications, illnesses, and additives found in alcoholic drinks can also produce similar symptoms.

Alcohol intolerance is not dangerous in itself, but the symptoms can be quite distressing. Research also shows that people with an ALDH2 enzyme deficiency who continue to drink carry a higher risk for certain types of cancer. For this reason, people with alcohol intolerance are advised to avoid alcohol.

Symptoms

The symptoms of alcohol intolerance typically appear immediately or very shortly after drinking. Even a small amount of alcohol can trigger them.

• Flushing of the face and neck. This is the most noticeable and most common symptom. The skin suddenly turns red and a feeling of warmth develops. It can sometimes spread to the neck and chest.
• Nausea and vomiting. Stomach discomfort, nausea, and occasionally vomiting may occur.
• Rapid or irregular heartbeat. Palpitations or a sense of a racing pulse may be felt.
• Headache. A headache can develop shortly after drinking.
• Nasal congestion or runny nose. Swelling of the nasal lining can cause congestion or a runny nose.
• Bloating and abdominal discomfort. Digestive symptoms may also accompany the picture.
• Drop in blood pressure and dizziness. In some people, a mild drop in blood pressure and resulting dizziness can develop.
• Itching or redness of the skin. Itching and redness can appear on various parts of the body.

Symptoms are generally temporary and ease as the alcohol is metabolized. Their severity, however, varies from person to person and depends on the amount consumed.

It is important to distinguish between alcohol intolerance and a true alcohol allergy. A genuine alcohol allergy is very rare and involves the immune system. It can cause serious reactions such as anaphylaxis. In alcohol intolerance, the immune system plays no role and symptoms are generally milder.

When to See a Doctor

• If you experience uncomfortable symptoms every time you drink even a small amount of alcohol, ask for a medical evaluation.
• If symptoms are becoming more frequent or more severe over time, see a doctor.
• If serious symptoms such as shortness of breath, throat swelling, or a significant drop in blood pressure develop after drinking, seek medical attention promptly. These may point to an allergic reaction.
• If you suspect that a medication you are taking may be causing alcohol intolerance, consult your doctor.

Causes

Alcohol intolerance can have more than one cause. The most common are as follows.

• Genetic enzyme deficiency. This is the most common cause. Insufficient functioning of the ALDH2 enzyme — which is responsible for breaking down alcohol — leads to a build-up of acetaldehyde in the blood. This is particularly common in people of East Asian descent (Chinese, Japanese, and Korean) and is also known as the "Asian flush." It is an inherited condition and cannot be changed.
• Sensitivity to additives in alcoholic drinks. Various substances used in the production of alcoholic beverages can cause symptoms. Histamine and sulfites found in wine, and yeast and grain proteins found in beer, are among these. In this case, the person is sensitive not to the alcohol itself but to a component of the drink.
• Medications. Some medications can produce intolerance-like symptoms when combined with alcohol. Metronidazole, chloramphenicol, and certain antifungal medications can have this interaction. Disulfiram, used in the treatment of alcohol dependence, is specifically designed to produce this effect as a deterrent.
• Illness. Certain conditions such as Hodgkin lymphoma can cause pain or discomfort after drinking alcohol. Liver disease can also disrupt alcohol metabolism and lead to intolerance symptoms.
• Wheat or grain sensitivity. In people with celiac disease or gluten sensitivity, grain-based alcoholic drinks such as beer can trigger symptoms.

Diagnosis

Alcohol intolerance is generally diagnosed through a review of symptoms and medical history. There is no specific diagnostic test.

• Detailed medical history. Which alcoholic drinks cause symptoms, when and how symptoms appear, and family history are all assessed.
• Elimination approach. Comparing whether different alcoholic drinks trigger symptoms can help determine whether alcohol itself or a specific additive is responsible. If only wine causes symptoms, for example, sulfites or histamine may be to blame.
• Allergy testing. An allergy evaluation may be performed to rule out a true alcohol allergy. A skin prick test and blood test can be used for this purpose.
• Investigation of underlying conditions. Liver disease or other possible causes are investigated. Liver enzymes and general blood tests are helpful during this process.
• Medication review. Whether any medications being taken could be contributing to alcohol intolerance is assessed.

Treatment

There is no definitive cure for alcohol intolerance. A genetic enzyme deficiency cannot be changed. The main aims of treatment are to prevent symptoms and address any underlying cause.

• Avoiding alcohol. This is the most effective and recommended approach. For people with a genetic ALDH2 deficiency in particular, avoiding alcohol both prevents symptoms and reduces the risk of cancer.
• Identifying and avoiding the trigger drink. If only certain drinks cause symptoms, stopping that drink may be sufficient. If symptoms are specific to wine, for example, avoiding wine while trying other drinks could be an option. This approach does not always work, however.
• Switching medications when a drug is the cause. If a medication you are taking is causing symptoms, your doctor may be able to suggest an alternative. This decision should be made under medical supervision — do not stop a medication on your own.
• Antihistamines. For symptoms related to additives, antihistamines can relieve itching and redness. These medications do not change how alcohol is metabolized, however, and do not treat the intolerance itself.
• Treating the underlying condition. If liver disease or another condition is the cause of the intolerance, treating that condition may improve symptoms.

Living with Alcohol Intolerance

Alcohol intolerance can significantly affect daily life. Avoiding alcohol in social situations can sometimes be difficult. With the right information and some practical steps, however, this is very manageable.

• Explore non-alcoholic alternatives. High-quality non-alcoholic drinks are becoming increasingly available. Choosing non-alcoholic options in social settings allows you to both protect yourself from symptoms and take part in social life.
• Read labels. If you are sensitive to additives such as sulfites or histamine, reading drink labels carefully can help you avoid your triggers.
• Inform your healthcare team. Whenever a new medication is being prescribed or a surgical procedure is planned, always mention that you have alcohol intolerance. Certain medications and anesthetic agents can interact with alcohol.
• Be aware of cancer risk. In people with an ALDH2 deficiency, drinking alcohol increases the risk of certain cancers, most notably esophageal cancer. Avoiding alcohol is therefore important not only for preventing symptoms but also for long-term health.

Preparing for Your Appointment

What you can do:

• Note which drinks cause symptoms.
• Describe when and how symptoms appear.
• Mention whether similar complaints exist in your family.
• List all medications and supplements you are taking.
• Write your questions down in advance.

Questions you can ask your doctor:

• What is causing my symptoms?
• Should I avoid all alcoholic drinks?
• Could any of my medications be contributing to my symptoms?
• Do I have an increased cancer risk?
• Could there be another underlying cause?

Your doctor may ask you:

• Which drinks cause symptoms?
• When do symptoms begin and how long do they last?
• Are there similar complaints in your family?
• What medications are you taking?
• Do you have liver disease or any other chronic condition?