Signs Your 'Hangover' May Actually Be An Alcohol Intolerance

When you have a few too many drinks, you might expect to wake up with a hangover and have nausea, a headache and extreme thirst. But you might not expect to experience these symptoms — along with flushed cheeks and a stuffy nose — after a single alcoholic beverage.

It can happen, however, and it might signal that you’re developing an alcohol intolerance, which doctors say can arise seemingly out of nowhere. Even if you’ve never had a problem drinking a couple of glasses of wine or a martini or two, one day you might find that these drinks hit a little differently.

“It comes up a fair amount,” Jeffrey Factor, an allergist-immunologist and fellow of the American Academy of Allergy, Asthma and Immunology, told HuffPost. “In reality, an alcohol intolerance is different from an alcohol allergy. Alcohol intolerances are much more common than a true alcohol allergy.”

Your symptoms could be triggered by the alcohol itself, or by other ingredients or chemicals found in alcoholic beverages, like wheat, barley, yeast or histamine, explained Rani Maskatia, an allergist-immunologist and medical director of Latitude Food Allergy Care.

“This is even further complicated when you talk about cocktails, which can be mixed with anything,” said Trevor Craig, corporate director of technical training and consulting at Microbac Laboratories, an independent testing lab.

If you start feeling unwell after drinking just a small amount of booze, you might want to get to the bottom of what’s going on. The only way to truly know is to see an allergist, Maskatia said.

Here are some things to know about the difference between an alcohol allergy and an intolerance, why you might suddenly experience symptoms after drinking, and what to do about it.

What’s the difference between an alcohol allergy and an intolerance? 

An alcohol allergy and an intolerance are sometimes confused, but they’re not the same, Factor said.

With an alcohol allergy, your immune system reacts to something in an alcoholic beverage, like an ingredient, preservative or chemical, according to the Cleveland Clinic. The immune system then triggers cells to release immunoglobulin E antibodies to neutralise the allergen, and that causes allergic symptoms, according to the Mayo Clinic. Factor said true alcohol allergies are pretty rare.

An intolerance, meanwhile, is any other type of reaction to alcohol that doesn’t involve the immune system, Factor explained. For instance, some people might not be able to metabolise alcohol properly. Intolerances can be genetic and are much more common than allergies, and may be more likely to affect people of East Asian descent, Factor said.

What’s confusing about the two conditions is that their symptoms can overlap, Maskatia said.

An alcohol allergy can cause a rash, swelling, vomiting and anaphylaxis in extreme cases. Flushing, nausea, vomiting, heart palpitations, headache, fatigue, stuffy nose and diarrhea are signs of intolerance, according to the Cleveland Clinic.

“So, you can’t look at a particular reaction and say, ‘Oh that’s definitely an allergy versus an intolerance to alcohol,’” Factor said.

How do you know if you have an allergy or an intolerance? 

It can be tricky, Factor said. “There’s really no good testing available for allergy to alcohol.”

Unlike other kinds of allergies, a skin test won’t specifically reveal an alcohol allergy, he explained.

However, doctors will talk to you about your symptoms and when you experience them, Maskatia said. “A clinical history is usually sufficient for an allergist to distinguish between a suspected intolerance and a suspected IgE-mediated allergy.”

A doctor might also do a blood or skin test, which can reveal allergies to substances in alcohol, such as yeast, barley, histamine, dairy or fruits, she explained. You can develop allergies to these substances at any age.

Why alcohol allergies and intolerances can develop later in life

It’s common for patients to come in describing symptoms or reactions to drinking alcohol that they only just developed, Factor said. It’s not clear why some people suddenly start experiencing these intolerances or allergies later in life.

Some people may be predisposed because of the onset of other medical conditions, like asthma, sinus diseases, medication allergies or changes to the body’s immune response, he explained. Genetics and environmental exposures are another factor, Maskatia said.

There’s also new research suggesting such changes could be COVID-related. In a small case study published in the journal Cureus in 2023, four patients with long COVID self-reported new alcohol sensitivities following their infections, with symptoms including headaches, grogginess, anxiety, mood changes, flushing and fatigue.

What to do if drinking alcohol triggers a reaction

Under the Food Allergen Labelling and Consumer Protection Act of 2004, the Food and Drug Administration requires packaged foods to list allergens like milk, egg, wheat, fish, shellfish, nuts, soybeans and sesame. But Maskatia said this doesn’t apply to alcoholic beverages.

That’s because the Alcohol and Tobacco Tax and Trade Bureau, not the FDA, oversees alcohol, and it makes allergen labelling on booze voluntary, Craig said. So it’s not always evident what’s in the alcohol you’re drinking.

“It’s tricky since there isn’t a requirement for a label, so it’s not always easy to look at it and decipher,” Craig explained. “Plus, you might be ordering from a bar and not even have access to the bottle.”

Still, if you know that consuming grapes triggers symptoms for you, staying away from wine is a good idea, and if wheat or barley cause you problems, beer is best avoided. “If you don’t know what’s in your drink and your allergy is serious, then skip it,” Craig said.

There’s no treatment for alcohol allergy or intolerance, so Factor’s best advice is to avoid drinking it if you react to it. You can adopt a dry lifestyle or just avoid certain drinks that cause your symptoms.

“The bottom line is this: There’s no treatment, no testing of any significant value, and the solution is really just to avoid that alcohol, or alcohol in general,” Factor said. “It’s not a very pleasing solution for a lot of people, but that’s what it is.”