A drink or two gives most people an inner glow.
But for some, alcohol can also have an external effect, with skin reactions ranging from rashes, hives, or a bright red color.
Known as an alcohol withdrawal reaction, this phenomenon results from several different causes, including heredity, allergies, and medications.
Genetics is responsible for many cases, as some people have a gene mutation that makes it very difficult to metabolize alcohol.
Understanding why this happens requires a quick chemistry lesson. To break down alcohol, whether it’s in beer, wine, or hard liquor, the body needs an enzyme called alcohol dehydrogenase.
It converts alcohol into acetaldehyde, a toxic molecule.
In most people, another enzyme, aldehyde dehydrogenase, kicks in. But some, especially many of Asian descent, have a genetic deficiency of an enzyme that helps break down alcohol.
“Without it, they may only take a few sips before starting this flushing,” says Corewell Health allergist Karin Gell, MD.
Flushing is only part of the discomfort that comes with this toxic byproduct.
“Your heart rate may go up. You may feel nauseous. You feel terrible because you’re inviting a poison that you can’t break down,” says Dr. Gell.
There is ongoing research into ways to address this problem, he said.
But the effort poses a moral challenge for scientists. Drinking any alcohol is known to increase the risk of certain types of esophageal cancer in those with this genetic mutation. And in the general population, even moderate drinking is associated with higher rates of head, neck, breast, and colorectal cancer.
There is also a risk of people becoming addicted to alcohol. About 5.8% of people 18 and older have an alcohol use disorder.
“These risks raise questions about whether it is reasonable to allow genetic modification for this enzyme deficiency,” he said. “Allowing people to drink increases the risk of some serious health problems.”
A tendency to blush
The alcohol spill response is not limited to any one segment of the population.
“Some people just tend to blush,” Dr. Gell said. That group includes many people who have rosacea, which affects some fair-haired, lighter-skinned people. “They just blush or blush more easily.”
People who have had hives or hives are also more susceptible. About 20% of the population has experienced these itchy bumps and spots at some point.
“Many of them will tell us. “If I have just a little bit of alcohol, my hives will come out,” Dr. Gell said.
Alcohol is a vasodilator, which means it makes blood pump to the skin. And it can be related to underlying allergies and sensitivities.
Others may experience nasal congestion almost as soon as they lift the glass.
These allergic reactions can be complicated, Dr. Gell said. And because beer, wine and spirits are made from a vast world of ingredients, sniffing out the culprit can be difficult.
“Alcohol can react with some powders,” he said. “As many of these hoppy beers have become more popular, I’ve had more people say, “Why am I having all these problems when I drink beer at a microbrewery?”
Hops, the flowers that give beer its bitterness, flavor and aroma, can cross-react with grass, he said.
“Often these same people will say, ‘Oh, and I have terrible spring allergies.’
Red wines contain histamines, which are also problematic for some people. Many people blame sulfites for this problem, and the Internet is full of apparent solutions.
Dr. Gell remains skeptical of them.
“I couldn’t find any medical studies on their effectiveness,” he said.
“I even read of a case where a man who drank red wine all his life had a terrible allergic reaction. The problem was which kind of oak the barrel was made from.”
Part of allergists’ detective work involves deciding the right tests to give patients, he said. Many things that can be in an alcoholic drink also include foods high in histamines, such as fermented foods, shellfish, and eggplant, and high in tyramine, such as aged cheese and cured meats.
“Often we can get clues when people tell us they can’t eat certain foods, like strawberries or tomatoes,” says Dr. Gell. “They can also make them feel red, itchy or nauseous.”
To drink or not to drink?
Over the years, Dr. Gell has heard many strategies when people are looking for tricks and gimmicks that will allow them to have a few drinks every now and then that don’t fill up.
Even if people have never had an alcohol flush reaction, she recommends being alert to changes, especially after starting a new medication.
Alcohol can cause dangerous reactions with so many medications, including common antibiotics, antifungals, malaria treatments, and some diabetes medications.
“When people get these drugs from the pharmacy, they come with warnings not to drink alcohol, but so many people don’t read them,” he said.