Questions come up from time to time from people who believe they may have an alcohol allergy. So I thought it might be helpful to provide an overview of alcohol allergies -- what they are, how to know if you might have one, and how to deal with them.

Let's face it -- if you overindulge in alcohol, whether it's all the time or just every now and then -- you're probably going to feel sick the next day. Pounding headache, nausea and shakiness are the classic symptoms of a hangover.

But some people feel sick after drinking even small amounts of alcohol, and although it's slightly possible they are just overly sensitive to the intoxicating effects of the alcohol, it might be that they are actually overly sensitive to ingredients found in the alcohol.

In reality, this is more of a food intolerance than a food allergy. Still, it can be a bother to deal with.

What You're Really Allergic To

Chances are, if you do have alcohol allergies, it's not actually to the ethanol in the alcohol you've drunk. It's more likely that you're having a food allergy reaction to one of the other ingredients, namely:

• Gluten/wheat. Gluten sensitivity is fairly common. It could take the form of a short-term gastrointestinal upset, which is called gluten intolerance. Or it could be a more severe autoimmune disease called gluten hypersensitivity or Celiac disease. Dr. James Thompson, another of our experts, covers the differences in greater detail. Neither one of these conditions, though, is a true food allergy. Gluten is found in rye, barley and wheat. Some people do have an allergy to wheat and wheat products. Malted barley, which contains gluten, and wheat are both used to make beer, so people who seem to have an alcohol allergy could actually have a sensitivity to gluten or wheat. Oddly, distilling rye, wheat and barley, as is done when making vodka, whiskey, gin and bourbon, seems to prevent allergic or intolerance reactions in people otherwise sensitive to beer or wine.

• Histamine. This protein is commonly found in red wine, as well as many other alcoholic beverages. Histamine, a natural substance found in our bodies, is directly involved with the allergic process. So, it is probably responsible for many intolerance-type reactions in people who think they have an alcohol allergy. Have you ever heard of "red wine headache"? It's real!

• Sulfites. These are sulfur-containing compounds naturally found in wine and beer. They help prevent bacteria (germs) from growing in these liquids, while they are aging, so sometimes extra sulfites are added by the manufacturer. Sulfites can trigger severe allergic reactions (anaphylaxis) and/or asthma attacks in sensitive people, although the severity of the response is directly related to the amount of alcohol that you drink.

• Yeast. A fungus called Brewer's yeast is used as part of the fermenting process in beer, wine, hard cider, sake and other beverages like those. Allergies to this type of yeast are quite common in people also allergic to mold.

• Grapes. This is not a common food allergy, but some people are allergic to grapes, so obviously wine is out. But if you're allergic to grapes, you should also avoid ouzo, vermouth, cognac and champagne.

• Corn. Corn is always used in the production of bourbon. But it may also be used to produce some beers and other hard liquors. Some people have an intolerance to corn proteins. It is believed that distilled alcohols such as bourbon and whiskey do not contain the actual corn protein that triggers symptoms, but there is not enough scientific evidence to be 100 percent sure.

• Artificial flavorings and color. Finally, if you are allergic to certain artificial colorings or flavorings, that might be the culprit in any reactions you have to alcohol, especially in liqueurs or brandies.

How to Tell if You Have an Alcohol Intolerance