Alcohol

Allergic reactions to alcohol

That being said, there are a small number of people who are allergic to alcohol. As little as 1ml of pure alcohol, which is the equivalent of 10ml of wine or a mouthful of beer, is enough to provoke severe rashes, difficulty breathing, stomach cramps or collapse in some people. Alcohol can also increase the likelihood of severe allergic reactions — anaphylaxis — from other causes like food.

Alcoholic beverages contain ethanol and other substances

The liver breaks down the alcohol (ethanol) we drink and converts it to a chemical called acetaldehyde. Acetaldehyde is then transformed to acetic acid ("vinegar"). Problems occur if alcohol can’t be broken down. As well as ethanol, alcoholic beverages contain a complex mixture of grape, yeast, hop, barley or wheat-derived substances, natural food chemicals (eg salicylates), wood-derived substances or preservatives like sodium metabisulphite. Severe allergic reactions have been described in people with allergies to proteins within grapes, yeast, hops, barley and wheat. These patients are not sensitive to alcohol itself. Furthermore, "fining agents" (like egg protein and seafood proteins) are sometimes used to remove any unwanted organisms, cloudiness or fermentation. “Fining” is a clarification technique where an agent is used to encourage solids to fall out of suspension so that the clear wine can be racked off. Whether these occur in sufficient amounts to trigger allergic reactions is unknown.
 

Allergy tests to alcohol are usually negative

The human body constantly produces small amounts of alcohol itself. Normal levels of 0.01 to 0.03 mg of alcohol/100 ml are contained in the blood. Since the human body produces alcohol itself, it is not known why some people develop allergic reactions when they drink alcohol. Allergy tests using alcohol are usually negative, but are sometimes positive to breakdown products of ethanol such as acetaldehyde or acetic acid ("vinegar").
 

Asthma and alcohol

Some people with asthma complain that wine worsens their asthma, more so than beer or spirits. Beer, wine and champagne contain sodium metabisulphite (additive 220, 221), which is a key preservative. Also referred to as 'sulphites', it is a naturally occurring compound found on many growing plants (including grapes) in its natural form. Since Roman times winemakers have added additional sulphur dioxide to their wines. Sulphur dioxide has strong anti-bacterial properties, which help to prevent organisms from growing in the wine. It also inhibits yeast growth, thus preventing the wine from turning into vinegar, giving it a longer shelf life, and enabling it to develop the complex flavours of an aged wine.

Some people, particularly those with unstable or poorly controlled asthma, may wheeze when they consume these drinks. Other reactions may include hives. Bear in mind that sulphur dioxide is present in many drinks other than beer and wine, including some fruit juices, along with various dried fruits. If you do not react to these products, then it may be another component of wine you are reacting to.

The sweeter the wine - particularly white - the higher the presence of sulphur dioxide. A person suffering from a sulphur allergy, then, may experience a lesser reaction to a full-bodied red due to its lower content of sulphites. (Unless, of course, they have allergies to ingredients found in red wines!)

Asthma can also be due to enzyme deficiency. Those with low levels of aldehyde dehydrogenase accumulate high levels of acetaldehyde after drinking alcohol, as they can’t break it down easily. Acetaldehyde has been blamed for asthmatic reactions to alcohol in up to half of Japanese asthma patients.
 

Histamine

Histamine is an amine released by the body tissues in allergic reactions, causing irritation. Red wines contain a wider range of components than white wines, and this includes histamines. Histamine can trigger sneezing, runny nose and sometimes wheeze, stomach upset and headache. If you think your reaction is due to the histamine component of the wine, then you could consider trying fruit wines, as some of these have lower histamine levels than wine made from grapes (depending on the fruit used to produce the wine).
 

The presence of alcohol may not always obvious There are many less obvious sources of alcohol in our diet. These include alcoholic soft drinks, mixes, spiked drinks, food marinades or tomato puree. Over-ripe fruit can ferment, resulting in enough alcohol production to trigger a reaction. Some medicines like cough syrups and some injected medicines also contain alcohol to help them dissolve and stay in liquid form.

Management of alcohol allergy Accidental exposure may lead to unexpected reactions. People with alcohol allergy should be managed in the same way as others with serious allergic reactions: identify and avoid the cause, wear a MedicAlert bracelet, and carry adrenaline as part of an emergency action plan if they are at risk of dangerous allergic reactions in the future.

Milder reactions to alcohol may also occur Alcohol sometimes worsens symptoms in people with hives / urticaria. Occasionally, alcohol can also trigger hives. As with more serious allergic reactions, the mechanism is unclear. Contact rashes from alcohol are very uncommon.

References: Australasian Society of Clinical Immunology and Allergy