Alcohol intolerance can cause immediate, uncomfortable reactions after you drink alcohol. The most common signs and symptoms are stuffy nose and skin flushing.

Alcohol intolerance is caused by a genetic condition in which the body can't break down alcohol efficiently. The only way to prevent these uncomfortable reactions is to avoid alcohol.

Although not a true allergy, in some cases, what seems to be alcohol intolerance might be your reaction to something in an alcoholic beverage — such as chemicals, grains or preservatives. Combining alcohol with certain medications also can cause reactions.

Signs and symptoms of alcohol intolerance — or of a reaction to ingredients in an alcoholic beverage — can include:

• Facial redness (flushing)
• Red, itchy skin bumps (hives)
• Worsening of pre-existing asthma
• Runny or stuffy nose
• Low blood pressure
• Nausea and vomiting
• Diarrhea

When to see a doctor

Having a mild intolerance to alcohol or something else in alcoholic beverages might not require a trip to a doctor. Simply avoid alcohol, limit how much you drink or avoid certain types of alcoholic beverages.

However, if you have a serious reaction or severe pain, see your doctor. Also, if your symptoms seem to be linked to an allergy or a medication you're taking, see your doctor.

Alcohol intolerance occurs when your body doesn't have the proper enzymes to break down (metabolize) the toxins in alcohol. This is caused by inherited (genetic) traits most often found in Asians.

Other ingredients commonly found in alcoholic beverages, especially in beer or wine, can cause intolerance reactions. These include:

• Sulfites or other preservatives
• Chemicals, grains or other ingredients
• Histamine, a byproduct of fermentation or brewing

In some cases, reactions can be triggered by a true allergy to a grain such as corn, wheat or rye or to another substance in alcoholic beverages.

Rarely, severe pain after drinking alcohol is a sign of a more serious disorder, such as Hodgkin's lymphoma.

Risk factors for alcohol intolerance or other reactions to alcoholic beverages include:

• Being of Asian descent
• Having asthma or hay fever (allergic rhinitis)
• Having an allergy to grains or to another food
• Having Hodgkin's lymphoma

Depending on the cause, complications of alcohol intolerance or other reactions to alcoholic beverages can include:

• Migraines. Drinking alcohol can trigger migraines in some people, possibly as a result of histamines contained in some alcoholic beverages. Your immune system also releases histamines during an allergic reaction.
• A severe allergic reaction. In rare instances, an allergic reaction can be life-threatening (anaphylactic reaction) and require emergency treatment.

Unfortunately, nothing can prevent reactions to alcohol or ingredients in alcoholic beverages. To avoid a reaction, avoid alcohol or the particular substance that causes your reaction.

Read beverage labels to see whether they contain ingredients or additives you know cause a reaction, such as sulfites or certain grains. Be aware, however, that labels might not list all ingredients.

Besides conducting a physical exam, your doctor might request these tests:

• Skin test. A skin test can determine whether you might have an allergy to something in alcoholic beverages — for example, the grains in beer. Your skin is pricked with a tiny amount of a substance that could be causing your reaction. If you're allergic to the substance being tested, you'll develop a raised bump or other skin reaction.
• Blood test. A blood test can measure your immune system's response to a particular substance by checking the amount of allergy-type antibodies in your bloodstream known as immunoglobulin E antibodies. A blood sample is sent to a laboratory to check reactions to certain foods. However, these tests aren't always accurate.

The only way to avoid alcohol intolerance symptoms or an allergic reaction is to avoid alcohol or the particular beverage or ingredients that cause the problem. For a minor reaction, over-the-counter or prescription antihistamines might help reduce symptoms, such as itching or hives.

Although alcohol intolerance usually isn't a serious issue as long as you don't drink alcohol, you might want to discuss it with your doctor at your next appointment. Here's some information to help you get ready for your appointment.

Make a list of:

• Your symptoms, including any that seem unrelated to the reason for which you scheduled the appointment, and when they occur.
• Key personal information, including major stresses or recent life changes. Stress can sometimes worsen allergic reactions or sensitivities.
• All medications, vitamins or supplements you take and the dosage.
• Questions to ask your doctor.

For alcohol intolerance, some questions to ask your doctor include:

• What do you think is causing my reaction to alcoholic beverages?
• Are any of my medications likely causing or worsening my reaction to alcohol?
• Other than the most likely cause, what are other possible causes of my symptoms?
• What tests do I need?
• What treatments are available?
• Do I need to give up alcohol?

Don't hesitate to ask other questions you have.

What to expect from your doctor

Your doctor might ask:

• When did you notice a reaction to alcoholic beverages?
• What beverages — beer, wine, mixed drink or a particular type of liquor — trigger your symptoms?
• How severe are your symptoms?
• How long does it take for symptoms to appear after drinking the beverage?
• How much of the beverage do you drink before you notice a reaction?
• Have you tried over-the-counter allergy medications, such as antihistamines, for your reaction, and if so, did they help?
• Do you have allergies, such as to particular foods or to pollens, dust or other airborne substances?

What you can do in the meantime

Avoid the beverage or beverages that seem to cause your reaction until your doctor's appointment.

If you drink a beverage that causes a mild reaction, over-the-counter antihistamines might help relieve symptoms. However, for a severe skin reaction, weak pulse, vomiting or trouble breathing, seek emergency help right away, as you could be having an anaphylactic reaction.