Could COVID Have Given You New Allergies? Here's What Doctors Are Finding

If you've noticed new allergies popping up since you had COVID-19, you're not alone. Medical centers across the country are reporting a striking pattern: patients who recovered from the virus are developing asthma, food allergies, and environmental sensitivities they never had before. And emerging research is starting to explain why.

The Numbers Tell a Clear Story

Multiple large-scale studies have documented this connection. Researchers analyzing data from over 22 million people across South Korea, Japan, and the United Kingdom found that the overall risk for developing allergies was approximately 20% higher in people who had COVID compared to those who never had the disease.

When researchers looked at specific conditions, the numbers were even more striking. After a COVID-19 infection, people were 74% more likely to develop chronic rhinosinusitis (persistent sinus inflammation), 66% more likely to develop asthma, and 37% more likely to develop allergic rhinitis (hay fever-like symptoms).

Interestingly, people who were vaccinated but never infected showed significantly lower risks for these same conditions, suggesting that vaccination may offer some protective benefit.

What's Happening Inside Your Body?

The culprit appears to be immune system dysfunction. Researchers at Harvard School of Medicine found that long COVID is associated with persistent immune dysregulation—meaning the immune system gets stuck in a state of chronic inflammation and exhaustion. This altered immune state appears to make the body more prone to allergic reactions.

One particularly interesting finding involves mast cells, which are immune cells that release histamine (a chemical that triggers allergy symptoms like itching, swelling, and inflammation). Experts suspect that COVID-19 may activate these mast cells abnormally, leading to what's called mast cell activation syndrome (MCAS). This could explain why some long COVID patients develop sensitivities to high-histamine foods like fermented foods and nightshade vegetables, as well as reactions to scented products like perfumes and detergents.

Real Stories From Real People

Long COVID centers are seeing diverse allergic presentations. One patient reported developing allergies to legumes, vegetables, dust, and laundry detergents after having COVID—when previously they'd only been allergic to milk. Another noticed that childhood asthma, which had been quiet for years, "came roaring back" after their COVID infection.

Medical directors at major health systems report seeing asthma, hives, environmental allergies, and food allergies as common new-onset conditions in their long COVID patients. The most frequently reported new allergy is asthma, though mast cell activation symptoms are also increasingly recognized.

What Comes Next?

Researchers are exploring whether early interventions might help. Some experts suggest that screening for new or worsening allergies early in recovery could help identify patients whose immune systems are heading in an "allergic direction." There's also interest in studying whether antihistamines or mast cell stabilizers given during acute COVID infection might prevent the immune changes that lead to permanent allergies.

If you've developed new allergies since having COVID, it's worth discussing with your doctor. Understanding that this connection exists—and that it's rooted in immune system changes rather than something you're imagining—is an important first step toward getting proper support and management.