When a food allergy appears after another condition, like COVID-19, it can be easy to wonder if the allergy and the illness are connected. This is even more true if the allergy seems to suddenly appear in a healthy person without a history of these kinds of allergic responses.

If you or your loved one had COVID-19 and later developed a food allergy, here is some information you need to know.

The Immune System and COVID-19

Research on how COVID-19 affects the body is ongoing. This includes studies on how it affects the immune system. Because COVID-19 is still relatively new, there’s a lot that researchers don’t yet know about this disease.

The immune system is designed to defend your body. Most of the time, it acts to get rid of dangerous invaders such as bacteria, viruses, fungi, and parasites. The immune system is made up of two parts. The innate immune system is also called the general immune system or the nonspecific immune system. It works fast to eliminate substances that shouldn’t be in the body.

When intruders get by the protections offered by the innate immune system, the adaptive immune system takes over. This part identifies invaders and learns how to fight off specific germs. It then remembers how to attack those germs, keeping that information for future use.

COVID-19 seems to affect both parts of the immune system. In one study, the innate immune system worked differently for up to a year after people had COVID-19. (The effect might last longer, but the study didn’t look beyond a year.) These cells experienced reprogramming on a genetic level. Those changes were passed on when the cells divided to make more immune system cells.

Those shifts in the innate immune system may be the reason some people experience long COVID symptoms after the initial infection is over. One specific immune chemical, a cytokine called interleukin-6, may be responsible for many of the symptoms of long COVID.

COVID-19 is active in the adaptive immune system too. Its T cells usually help the immune system respond effectively to invaders. In COVID-19, these infection-fighting cells seem to get used up and become fewer.

Researchers aren’t sure exactly why COVID-19 causes any of these changes. They need to do more work to uncover answers to all these questions.

Food Allergies and the Immune System

Food allergies are caused by an immune system response. When you develop a food allergy, your immune system sees a specific food protein as a threat and becomes very sensitive to it. Any protein that triggers an allergic reaction is called an allergen.

In some people, white blood cells begin producing substances called immunoglobulin E (IgE) antibodies the first time the immune system encounters a food allergen. When you’re exposed to the food allergen again, IgE antibodies trigger immune cells to release other chemicals that cause your allergy symptoms.

Evidence for New Food Allergies After COVID-19

Researchers don’t know yet if the immune system changes that can happen after a COVID-19 infection can lead to new allergies, including food allergies. There’s some evidence that COVID-19 and allergies, in general, are connected.

One study suggests that people who’ve had COVID-19 are 20 percent more likely than those who haven’t had the illness to develop an allergic disease. However, the researchers didn’t find a higher risk of developing food allergies, specifically. Some people living with long COVID have said that they’re noticing new food allergies. This type of claim hasn’t been either proved or disproved by research yet.

There’s some evidence that having a food allergy already makes you less likely to get COVID-19. There’s also evidence that people who have allergies and get COVID-19 are more likely to end up with long COVID. These findings don’t speak specifically to questions about new food allergies after COVID-19. They do, however, seem to indicate some sort of link between allergies and COVID-19 that needs careful examination by researchers.

Without more evidence, we need to be careful not to say that COVID-19 causes new allergies. Sometimes, situations occur after each other, but the first doesn’t cause the second. Researchers need to show not only that COVID-19 and allergies have a connection but also that one somehow causes changes with the other. They haven’t done that yet.

In general, we don’t have enough information to fully understand any links between COVID-19 and new food allergies. That doesn’t mean that they don’t exist. It does make it hard to know why some people may experience new food allergies after having COVID-19. Researchers continue to study these areas, and someday we’ll likely have the answers we’re looking for.

Work With Your Allergist

If you or someone you love is experiencing a new food allergy, talk to an allergist right away. You may have to see your regular health care provider first to get a referral. If your allergy team thinks you need it, they may also send you to an immunology specialist. These doctors have the most up-to-date understanding of how the immune response from COVID-19 may affect the development of new food allergies.

Your allergist can also help you find effective ways to live with a new food allergy. You may end up with medication and a visit to a registered dietitian. That person will help you come up with ways to live and eat well while avoiding the foods that cause your allergy symptoms, such as a rash (hives), shortness of breath, an itchy or stuffy nose, sneezing, and anaphylaxis (a potentially fatal reaction).

Talk With Others Who Understand

MyFoodAllergyTeam is the social network for people with food allergies and their loved ones. On MyFoodAllergyTeam, more than 41,000 members come together to ask questions, give advice, and share their stories with others who understand life with food allergies.

Have you wondered if there’s a connection between food allergies and COVID-19? Share your experience in the comments below, or start a conversation by posting on your Activities page.