Alcohol intolerance: symptoms, causes, tests and what to do

Patient.info says the term alcohol intolerance is used for people who cannot process alcohol in the normal way, and that they often have an affected gene that is passed down in the family. The symptoms are described as arising from a build-up of acetaldehyde, a chemical produced when the body breaks alcohol down.

The NHS explains the wider category: a food intolerance is when you have difficulty digesting certain foods or ingredients, and it is not usually serious, although eating the food you are intolerant to can make you feel unwell. The NHS lists alcohol, histamine (found in wine and cheese) and sulphites (found in cider, beer and wine) among the things a person can be intolerant to.

Patient.info separates alcohol intolerance from having a low tolerance. A low tolerance is a social term for someone who feels the effects of alcohol much quicker than others, and people with a low tolerance can continue to drink as long as they know their limits and do not exceed the recommended units.

Patient.info says that if you have alcohol intolerance you will likely experience one or more of headaches, nausea, vomiting and a rapid heartbeat. The NHS notes that, for food intolerances generally, symptoms usually start a few hours after eating the food and can last for a few hours or days, and that diarrhoea, bloating, farting and tummy pain are common.

Patient.info adds that experiencing these symptoms does not guarantee an alcohol intolerance, because your body might instead have difficulty with other constituents of alcoholic drinks, such as histamine, yeast, grains, sulfites or preservatives.

• Headache.

• Nausea and vomiting.

• A rapid heartbeat.

• Other symptoms common in food intolerance, according to the NHS: diarrhoea, bloating, farting, tummy pain, tiredness, joint pain or rashes.

Patient.info says the difference between alcohol allergy and intolerance can be difficult to tell, because the symptoms can be similar. True alcohol allergy is thought to be rare, but allergic reactions can be strong and, in some cases, lead to anaphylaxis, which can be fatal.

The NHS says an allergy involves the immune system overreacting, whereas a food intolerance does not, which means you cannot have a serious allergic reaction from an intolerance. A reaction that looks like intolerance may in fact be an allergy to another ingredient, so any signs of allergy after drinking should be treated seriously.

Patient.info says people with alcohol intolerance often have a gene that is affected and passed down in the family, and that the symptoms occur because acetaldehyde, which the body normally breaks down, builds up.

The NHS says a food intolerance is caused by your body not being able to digest a certain food or an ingredient in food. Alcohol, histamine, sulphites and other ingredients are on the NHS list of things a person can be intolerant to.

Patient.info says self-diagnosis of alcohol intolerance or allergy is not advised, and that you should seek help from an immunologist at a specialist allergy clinic. It describes a skin prick test, in which a drop of alcohol is applied to the skin before it is pricked with a fine needle and observed, and a blood test to check IgE antibody levels. A positive result would mean an allergy to alcohol.

The NHS says that for food intolerance a GP may refer you to a dietitian, and that tests may include a special diet to avoid the suspect food to see if symptoms improve, followed by reintroduction, and a food and symptoms diary. It says some home tests that claim to diagnose food intolerances are not recommended, because there is limited evidence that they give accurate results and they may suggest avoiding multiple foods, which can be harmful.

Patient.info says the treatment is avoiding alcohol, and that people with alcohol intolerance should try to limit or abstain from alcohol consumption entirely. It acknowledges that cutting out alcohol completely may not feel realistic if it was a big part of someone’s lifestyle, and that stopping suddenly can take a toll on mental health, so it recommends establishing a support system.

The NHS general advice for food intolerance is to avoid or reduce the food you are intolerant to, but not to cut foods out of your diet without advice from a GP or dietitian, because you could miss out on vitamins and minerals.

Patient.info says that continuing to drink while intolerant is likely to cause liver damage, and that inflammation of liver tissue can lead to fibrosis and ultimately cirrhosis and liver failure. It says there is also an increased risk of liver cancer if you continue to drink while intolerant.

More generally, Patient.info notes that studies have identified a link between alcohol consumption and certain cancers, including breast, head and neck, and oesophageal cancers, and that the more alcohol a person consumes, the higher the likelihood. It also says people can become more tolerant of alcohol over time, which can lead to dependency and withdrawal symptoms.

The NHS says to see a GP if you have symptoms of a food intolerance that keep coming back. Patient.info says that if you experience severe symptoms of alcohol allergy or intolerance, you should limit or abstain from alcohol while you seek a diagnosis from your GP or an allergy specialist.

The NHS lists signs of a serious allergic reaction that need a 999 call: sudden swelling of the lips, mouth, throat or tongue, breathing very fast or struggling to breathe, a throat that feels tight or difficulty swallowing, skin, tongue or lips turning blue, grey or pale, or suddenly becoming very confused, drowsy or dizzy. Patient.info says that if you ever have allergy symptoms after drinking alcohol, you should call 999 without delay.

On the NHS the first step is usually a GP, who may refer you to a dietitian or an allergy service. Patient.info advises seeing an immunologist at a specialist allergy clinic if an alcohol allergy is suspected.

Private allergy clinics also offer skin prick and blood testing. Whatever the route, the diagnosis should come from a clinician rather than an unvalidated home test.