What Long COVID Does To Your Alcohol Tolerance

Beer lovers like most of our readers will be distressed to learn that alcohol intolerance is one of the many symptoms of long-COVID. Recent studies show that long-COVID leads to significant complications in alcohol metabolism.

I have been writing about beer history and the alcohol markets in Canada for over two years now, and as a proud craft beer enthusiast, this is close to heart. At the time of publication of this article, I’ve been suffering from long-COVID for six months. Many other microbrewery beer lovers have seen their resistance to alcohol plummet. A good friend of mine, Catherine Dionne-Foster, founder and owner of La Korrigane microbrewery, told me that she was off work due to COVID-19. But that is just a drop in the bucket. Over 15% of people who contracted COVID suffered one or several long-term COVID-19 symptoms. That’s easily 3% of the population in Canada and in the United States.

In the United States, data from late 2023 suggests that about 25.6% of adults who contracted COVID-19 reported experiencing long COVID symptoms at some point after their initial infection, though this percentage has been gradually decreasing. Currently, around 9.5% of those who have had COVID-19 are actively experiencing long COVID symptoms.

More than a sensitivity to alcohol, it’s a significant post-exertional malaise (PEM) that sets in after just one pint. Numerous people on social networks have expressed similar acute sensitivity to the harmful effects of alcohol.

How does long-COVID affect our ability to eliminate alcohol?

Before getting to the heart of the matter, let’s just touch briefly on how alcohol affects our body, and how the body acts to get rid of it. The ethyl alcohol molecule has an inhibitory effect on the autonomic nervous system. As its name suggests, this system manages vital functions beyond your control, such as regulating heart rate and digestion. But the list is actually much longer: it includes a wide range of actions from pupil dilation and sweating to blood pressure regulation, sexual responses, and saliva stimulation.

One of the most common problems associated with long-term is disruption of the autonomic nervous system, a phenomenon known as dysautonomia. Here are two ways alcohol affects the autonomic nervous system:

Blood vessels and dysautonomia: Alcohol dilates blood vessels, which can aggravate certain symptoms of dysautonomia. By dilating the veins, it becomes more difficult for the body to pump blood upwards, which can lead to feelings of dizziness and fainting.
Impact on sleep: Acetaldehyde, a by-product of alcohol metabolism, inhibits entry into the deep phases of the sleep cycle, which are essential for recovery. One study shows that even moderate amounts of alcohol can reduce sleep quality by 9.3% by disrupting deep sleep cycles.

A landmark Stanford study on alcohol and long-COVID

I looked everywhere for any significant studies on this, but the only one I found was conducted by Stanford University on a very small sample. Researchers there measured the impact of long-term COVID-19 on alcohol consumption by tracking its progression in four patients of different ages. In all cases, sensitivity to alcohol was observed.

One example is a 49-year-old woman who reported suffering from long-term COVID-19 for 11 months, during which time even moderate consumption of wine rendered her almost immobile. Another case involved a 40-year-old woman who, before COVID, consumed up to seven cocktails every evening, but after contracting it could no longer tolerate a single glass, reflecting a three-month struggle with the symptoms of long COVID.

Researchers explain that COVID-induced body inflammation could compromise the integrity of the blood-brain barrier, which could worsen hangover symptoms by allowing more harmful substances, such as alcohol, to enter the brain.

That study left with with more questions than answers. What actually explains how long COVID affects our tolerance to alcohol? So I sent out a flock of emails to subject matter experts and chronic fatigue researchers, thinking that maybe this would help. No one had anyone to refer to me, some politely telling me that with long-COVID, the alcohol issue was far from a priority. Then, one Saturday morning, I found an email from Mr. Alain Moreau, a researcher in Montreal. The message was brief: We have something you might be interested in. When are you available?

Chronic fatigue syndrome

Mr. Alain Moreau is the scientific director of the Laboratory of Molecular Genetics of Musculoskeletal Diseases at the Sainte-Justine University Research Center in Montreal, Quebec. He is also a specialist in myalgic encephalomyelitis, also known as chronic fatigue syndrome.

As it turns out, there is a whole lot in common between that and long-COVID. Chronic fatigue syndrome is a well-known topic to scholars, particularly where alcohol is concerned. A 2023 study indicates that over 60% of ME/CFS patients develop increased sensitivity to alcohol.

Based on clinical tests developed to identify the physical traces of chronic fatigue, Moreau and his team have identified a biomarker that could play a key role in the impact of long-term COVID-19 on alcohol tolerance: the FGF-21 protein.

FGF-21, the pandemic hangover protein

The FGF-21 protein is a molecule created by muscles and by the brain. It plays a key role in cardiovascular health: the Molecular Genetics Laboratory team identified abnormally high levels of this protein in long-COVID patients. The same high levels associated with encephalomyelitis.

What is a biomarker?
A biomarker is any molecule whose presence or quantity makes it possible to measure a biological process, such as a disease: for example, a mutation in a gene or a protein such as FGF-21. Glucose, for example, is the main biomarker for diabetes.

“In our chronic fatigue studies, we noticed that almost 9 times out of 10, people are intolerant to alcohol. We realized in the biomarker study that in these patients, FGF-21 levels were abnormally high. When we started screening for long-COVID biomarkers, we realized very high levels of FGF-21 there too. ”

This study shows that what is generally referred to as long-term COVID-19 is less of a disease and more of a transition to chronic fatigue.

“With our new tools, we can differentiate between fibromyalgia, chronic fatigue syndrome, and long-COVID by studying patients’ microRNA profiles. Although these conditions have different microRNA profiles, I found that the same genes are involved in the development of symptoms similar to those of fibromyalgia. This indicates that there may be a common underlying mechanism for these diseases, despite their molecular differences.”

Which remedies are there for alcohol intolerance linked to long-COVID?

One positive aspect of his research concerns the use of naltrexone, an anti-inflammatory which, at low doses, appears to significantly improve the symptoms of these conditions. Clinical trials have shown that patients suffering from chronic fatigue or long-term COVID-19 who take naltrexone often have lower levels of FGF-21 protein, a biomarker associated with inflammation.

This research is still in its infancy, and Moreau stresses that we shouldn’t expect a panacea. Taking into account comorbidity, lifestyle, and genetic predisposition, naltrexone may work on only a third of people with alcohol intolerance linked to long-term COVID-19.

Beyond the question of alcohol tolerance, what these studies highlight is the long-term impact of COVID-19, even after the main symptoms have disappeared. The persistent symptoms of these diseases are akin to a premature aging process. Epigenetic markers reveal changes in affected young adults similar to those observed in older adults, potentially predisposing them to cardiovascular disease, type 2 diabetes, and possibly an increased risk of cancers. Recent studies tend to confirm this acceleration of aging in these patients.

What is there to do?

Current research has no definitive answer to whether you like good beer or good wine. However, we can take comfort in the fact that this one is a lesser evil among the many drawbacks caused by COVID-19.

Remember that alcohol is a toxic substance that attacks the nervous system, the brain, and the intestines, even in moderate quantities, according to the most recent studies.

For those caught up in the long COVID, it may be time to consider alcohol-free beers or cocktails. For those who, like me, are affected by this cocktail of bad news, I offer you my heartfelt encouragement. There is still plenty of chances to drink beer, but I’ll be toasting to moderation.

Extensive resources on treatment for long-COVID:

Syndrome post-COVID-19 (COVID longue), Santé Canada
New Alcohol Sensitivity in Patients With Post-acute Sequelae of SARS-CoV-2 (PASC): A Case Series, Cureous
Que sait-on de la Covid longue et comment la soulager? Agence France Presse
Close association between lifestyle and circulating FGF21 levels: A systematic review and meta-analysis, Frontiers

Pierre-Olivier Bussières is the Director of Sales with Uber Flix Studio and Editor-in-Chief of Hoppy History. He writes on alcohol markets, Search Engine Optimization, and podcast technologies. He previously wrote for Global Risk Insights, the Diplomat, Reflets, La Montagne des Dieux, the NATO Association of Canada, Diplomatie, and Le Temps d’une Bière.