What Are the Signs of an Allergic Reaction to Alcohol?

Symptoms of an allergic reaction to alcohol include congestion or a runny nose as well as asthma and nausea. An allergy to alcohol is also known as alcohol intolerance, as a person's body is physically unable to break down the alcohol. Other common signs of alcohol intolerance include flushing of the skin after drinking and a rapid heartbeat. Some people may experience migraines or suffer a life-threatening reaction to alcohol.

A seeming allergic reaction to alcohol can occur for a number of reasons. A patient may actually be unable to break down the alcohol due to a lack of the aldehyde dehydrogenase 2 (ALDH2) enzyme, which metabolizes alcohol once it is ingested. The lack of ALDH2 is genetic and commonly found in people of Asian or Jewish descent.

Other people who experience alcohol intolerance may actually be reacting to something in the alcohol, not the chemical itself. Histamines, found in beer and wine, can trigger symptoms such as congestion. Sulfites in wine may trigger asthma. Some people may be allergic to the grains used to produce the drink, such as wheat or corn.

Flushed, red skin is a common sign of an allergic reaction to alcohol. Reddening of the skin usually occurs when a person lacks the ALDH2 enzyme. The skin may also feel hot and may itch. Other than red, warm skin, a person missing ALDH2 may not experience other reactions to alcohol. Although drinking alcohol may cause no real harm to a person with ALDH2 deficiency, some reports suggest that those with ALDH2 deficiency may have a higher risk of cancer if they continue to drink.

Other signs of an allergic reaction to alcohol are similar to a standard allergic reaction. Some people may have a runny nose or congestion right after drinking. Asthma may become worse due to alcohol intolerance. These reactions are more likely caused by ingredients in alcoholic beverages, not the alcohol itself.

In rare cases, a person can suffer a severe reaction to alcohol, such as anaphylactic shock. If a person struggles to breathe or experiences swelling after drinking, he should go to the hospital for emergency treatment. Histamines found in alcohol can trigger migraines in a few people after drinking.

Some reactions to alcohol can be treated with antihistamines, available over the counter. People who suffer severe reactions to ingredients in alcoholic beverages may wish to carry an epinephrine pen with them to rapidly treat any reactions. The best way to avoid an allergic reaction to alcohol is to avoid drinking it altogether.