Before she came down with COVID in March 2020, Rebekah Stein was able to enjoy a handful of alcoholic drinks a week. She assumed nothing had changed after her mild infection, so when she saw her husband holding an enticing glass of whiskey one night, she took a tiny sip.
Within a minute, severe chest pain kicked in, and Stein, 30, became so drunk it felt like she had downed several drinks at once. The next day was worse, but it wasn’t your average hangover: She had an irregular heartbeat, chest pain, cough, sore throat, headache, and stuffy nose. It was “basically COVID relapse,” said Stein, who’s also dealing with other long COVID symptoms, including shortness of breath, regular fevers, full body aches, and exhaustion.
“When this was first occurring, I hadn’t connected the dots. I would wake up and take a COVID test because I had all the COVID symptoms, and when I drink my heart rate gets really high overnight,” Stein said. “My body seems to know it’s being poisoned pretty quickly.”
Nearly three years later, Stein still cannot drink alcohol of any kind. And she isn’t alone.
Post-COVID alcohol intolerance has not been studied yet, so no one knows how common it actually is, but interviews with doctors, researchers, and people who are no longer able to drink alcohol suggest it’s yet another mysterious symptom that could be a side effect of the viral infection.
Long COVID, also known as post-COVID conditions, occurs when health problems last for weeks, months or even years after a coronavirus infection. It was recognized by the American With Disabilities Act in 2021 and roughly 30% of adults may experience at least one COVID symptom that lasts three months or more, according to research.
Dr. Stuart Malcolm, an internal medicine physician who solely treats long COVID patients at the RTHM clinic, said many people with long COVID have given up alcohol entirely “because it seems to universally not make people feel well.” But he estimates that about 5% to 10% of his patients (or about 10 to 20 people in his practice) are experiencing this intolerance as they continue to experiment with alcohol consumption.
A neurologist with long COVID in Louisiana also wrote about her experience with it in a March 2021 blog post, and a Reddit thread from last February revealed more people dealing with the same problem.
Alcohol intolerance can happen even to those who aren’t experiencing long COVID, may disappear or become less severe with time, and can be triggered by specific types of alcohol but not others. Although inconvenient, not being able to drink alcohol isn't the most earth-shattering of symptoms compared with more serious effects.
Still, experts, particularly those who study or treat people with ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome) — a complex illness that shares many similarities with long COVID — aren’t too shocked to hear about the occurrence.
“It doesn't surprise me at all because we now know there are all sorts of underlying biological abnormalities in people with ME/CFS that involve the immune system, energy metabolism, brain, autonomic nervous system, and microbiome of the gut, most of which now are showing up in people with long COVID,” said Dr. Anthony Komaroff, a professor of medicine at Harvard Medical School who has studied ME/CFS for 35 years. “But what specifically the abnormalities are that lead to alcohol intolerance we don't know yet.”
What is alcohol intolerance?
Alcohol intolerance is generally an inherited metabolic disorder that prevents people from processing alcohol the way other people do; a genetic mutation makes a specific enzyme, or protein, less efficient at converting alcohol into a non-toxic substance, causing a buildup of toxins in the blood.
As a result, people’s face, neck, and chest become flushed — warm and pink or red in color — almost immediately after drinking alcohol. They may also experience stuffy nose, nausea, vomiting, rapid heartbeat, low blood pressure, headache, diarrhea, and worsening asthma.
The condition doesn’t go away, but people can manage it by avoiding booze of all kinds. People of Asian descent are more likely to have the genetic mutation, so they have the condition at greater rates compared with other racial groups.
Although it might feel like it, alcohol intolerance doesn’t make people get drunk faster, and it doesn’t increase blood alcohol levels. The condition is also different from an alcohol allergy, which is an immune response to a chemical, grain, or preservative in alcohol that can cause rashes, itchiness, swelling, and stomach cramps.
Both conditions can cause nausea, but an alcohol allergy is typically more painful and can be life-threatening if untreated.
When it’s related to long COVID or another chronic condition, however, alcohol intolerance likely harms the body through a different chemical mechanism that doesn’t involve an inherited genetic mutation or allergy, Komaroff said.
It’s also possible the coronavirus may directly affect the enzymes responsible for processing alcohol, said Dr. Vikrant Rachakonda, a hepatologist, gastroenterologist, and professor of medicine at UC Davis Health.
But that remains to be seen.
Why do some people have alcohol intolerance after COVID?
There are several plausible explanations behind post-COVID alcohol intolerance, but it has not been thoroughly studied. Most speculations are based on what scientists have learned about long COVID’s impacts on the body and research on ME/CFS.
Given how complex long COVID is, it’s unlikely that just one of these theories can fully explain what’s going on. Here are three of the main ones, according to experts.
The liver processes everything we consume, including alcohol, so when the organ is injured or weakened in any way, it becomes vulnerable to further injury when exposed to toxins, like alcohol, Komaroff said.
COVID can injure the liver in more ways than one, and some experts, like Malcolm, the long COVID doctor, suspects the disease causes “a little bit more injury to the liver than we thought that’s not apparent in standard lab tests."
That’s all to say that an injured liver — or an undiagnosed liver disease, which Rachakonda says is very common because most cases are symptomless — likely won’t process alcohol as it should. It’s possible that people who cannot tolerate alcohol after COVID may have sustained an acute liver injury from their infection or have an undiagnosed liver condition.
Rachakonda said it’s not unreasonable to request a blood test if you’re experiencing alcohol intolerance. Checking your liver enzymes, as well as your kidney function and electrolytes, can help rule out any other causes.
Mast cell activation
Mast cells are a type of immune cell that cause allergic reactions when they detect an allergen like proteins from peanuts. They do this by releasing a chemical called histamine, which works to get rid of the allergen by making you itchy, sneeze, nauseous, short of breath, etc. (Komaroff actually suspects alcohol intolerance post-COVID might even be a “kind of allergic reaction.”)
Studies show that long COVID exacerbates this process by activating mast cells, encouraging them to release extra histamine into the body. (ME/CFS also does this.) It can mimic the symptoms of mast cell activation syndrome, a condition that causes people to have repeated episodes of anaphylaxis-like symptoms, such as hives, low blood pressure, severe diarrhea, and difficulty breathing. (Anaphylaxis is a potentially life-threatening allergic reaction.)
Making matters worse, alcohol not only contains histamine — it’s a byproduct of the fermentation and brewing process — but it also pushes mast cells to release more of it and then blocks an enzyme called the DAO enzyme from breaking histamine down.
“It’s kind of a triple whammy,” Malcolm said. All the extra histamine may explain why some people feel terrible after drinking alcohol post-COVID.
This theory can also help explain why alcohol intolerance may disappear or become less severe over time. As your body clears the virus and begins to recover from the injuries it caused, there’s less chaos triggering your mast cells to release extra histamine.
That may be what happened to 26-year-old Serena Quinlan. When she got COVID in February 2021, she experienced loss of taste and smell for several weeks, which included a weird aversion to foods like onions and guacamole. However, after some nights out with friends and solo wine nights at home that involved only a couple drinks, Quinlan noticed her body acting as if she had at least eight, she told BuzzFeed News.
“For the rest of that spring and summer, I just really, really struggled if I had one drink. I would wake up so hungover, terrible headaches, and super tired,” said Quinlan, a law student in Tennessee. “It was so bizarre.”
Her friend who initially gave her COVID experienced the same symptoms: “She texted me on her own and asked me if I was also dying every time I drank alcohol,” Quinlan said.
After three months, her alcohol intolerance disappeared completely.
Blood flow issues
Many long COVID patients (along with ME/CFS patients) experience issues with their autonomic nervous system, which plays a critical role in how blood vessels constrict and dilate, but researchers don’t yet fully understand why.
When someone has long COVID or ME/CFS, their blood vessels can’t properly respond to signals from the brain to tighten or loosen up. This is why many people with long COVID feel lightheaded or even faint after standing up, as their blood vessels don’t constrict enough, causing blood pressure to drop. It’s a hallmark symptom of POTS (postural orthostatic tachycardia syndrome), which about 2% to 14% of people who test positive for COVID end up developing.
Now consider alcohol. Alcohol widens your blood vessels even more, further decreasing blood pressure. “If you've already got a loose hose that isn't responding to the signal to tighten up and you're making it looser with alcohol, that's going to worsen those symptoms,” including fatigue, rapid heartbeat, cognitive impairment, and more, Malcolm said.
This increased blood flow could also explain the intense body pain some people with long COVID or ME/CFS experience, according to Sarah Annesley, a microbiology senior research fellow at La Trobe University in Australia who studies both conditions.
Julie Harmon knows this sensation all too well. About a month after getting COVID in December 2020, she began to feel tingling, numbness, aches, and pain throughout her entire body. It wasn’t until the summer when Harmon, 39, noticed her alcohol intolerance. A half-hour after drinking one beer, her face would flush and her hands would hurt so much that she couldn’t hold a book or phone, or “do regular daily things,” Harmon told BuzzFeed News.
“My first few drinks, I was like, ‘oh well, this is just my long COVID pain.’ But when I would have a glass of wine with dinner, I'd feel terrible again,” the Arkansas resident said. “So it finally dawned on me that even small sips of alcoholic drinks were exasperating my symptoms quite a lot.” Harmon now avoids alcohol entirely.
What to do if you are experiencing alcohol intolerance after COVID
It’s safe to say an intolerance to alcohol isn’t the worst of COVID or long COVID symptoms, but it can take away the “happy” in happy hour and generally impact your social life (if it revolves around alcohol at all).
The good news is that you can avoid alcohol intolerance by avoiding booze altogether. You’ll also want to avoid drinking alcohol when taking certain medications, as some drugs can worsen symptoms of alcohol intolerance. Taking antihistamine medication is another no-go because it may hide some symptoms and lead you to drink more.
Otherwise, Malcolm suggests drinking plenty of water to stay hydrated and possibly pursuing some blood work to better understand what may be causing your symptoms. A low histamine diet could help too, which excludes most fermented products like wine, beer, and cured cheese. Some other foods to consider avoiding include fish, tomatoes, spinach, citrus fruits, eggs, and chocolate.
But ditching alcohol really is your best bet, Malcolm said: “The hard part is that alcohol is such a social thing, but try to find something else that can help you relax.”