Hangover or alcohol intolerance? How to tell the difference

Hangovers, aka the aftermath of drinking alcohol, have quite the shopping list of symptoms – headache, nausea, intense thirst, tiredness and brain fog.

But, some symptoms people assume are hangovers may actually be caused by alcohol intolerance or allergy.

While many of us enjoy an alcoholic drink, the bad news is alcohol’s a toxic substance.

When we feel hungover, this is our body converting it into non-toxic substances. The length and severity of hangovers can vary, depending on the strength and amount of alcohol consumed, and the rate our body can process it.

Dehydration can also be responsible for our hangover symptoms, from headaches and fatigue to anxiety and sensitivity to light and sound, says Dr Timothy Watts, a consultant physician in adult allergy at The London Clinic.

What’s the difference between a hangover and alcohol intolerance?

People with alcohol intolerance often suffer from severe hangover-like symptoms due to a genetic metabolic disorder, external, which “causes the body to process or metabolise alcohol incorrectly,” Watts says.

When we drink alcohol, an enzyme called aldehyde dehydrogenase (ALDH) helps us to recover and transform the toxins into acetic acid (aka vinegar!).

Older adults have less ALDH, which explains why hangovers can feel worse with age.

Those with a genetic intolerance have a mutated version of ALDH, which leads to more unpleasant symptoms, says Watts, such as “extensive skin flushing, nausea, vomiting, palpitations, headache and fatigue”.

What alcohol intolerances can cause hangover-like symptoms?

Some people are intolerant to the ingredients in alcohol, not the alcohol itself, such as histamine, external and salicylates, external (found in wine, beer, rum, and sherry).

Others, including up to 13% of asthmatics, external, are intolerant to preservatives in alcohol called sulphites.

Symptoms can include a stuffy or runny nose, headaches, hives, itchiness, wheezing and tummy upset, but reactions can be life–threatening, external.

Alcoholic drinks high in sulphites and/or histamine include wine, cider and beer. But, some varieties of gin and vodka, as well as natural wines are low in sulphites