Can Allergies Cause Fever? An Immunology Doctor Responds

Updated: Mar. 10, 2023

A board-certified immunologist clears the air—turns out, there's only one potential case when allergies cause fever.

Wondering if your allergies are causing the fever you seem to be experiencing right now? When the symptoms of allergies seem so similar to an infection, like COVID or a cold, it can feel confusing to try and differentiate between seasonal allergies and a virus…especially when your head’s a little foggy.

Allergy symptoms typically include sneezing, nasal congestion, watery and itchy eyes, as well as coughing or trouble breathing due to congestion. But can allergies cause fever, as well?

The Healthy @Reader’s Digest asked Dr. Andrea Burke, MD, a New York City-based board-certified allergist and immunologist, whether allergies can cause fever—and what triggers a fever response in the body.

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Fever is an inflammatory response unrelated to allergies

According to Dr. Burke, the answer is no: A fever does not occur if you’re dealing with allergies. “Fever is a response of the immune system that is triggered by an infection,” she says. “In the context of inflammatory reaction like a virus or a bacterial infection, those are the most common of a fever.”

Fever is the body’s natural, biological response when it’s working to kill off an infection. The body’s temperature raises because the infection is able to thrive at a normal temperature—but at a higher temperature, it is harder for the infection to survive. This is how genius your immune system is!

Burke also points out that a fever triggers the immune system for other types of inflammatory conditions besides infection, such as Crohn’s disease and rheumatoid arthritis. “These two things cause an inflammatory response, and the infection is a different response from the allergic immune system,” Burke explains. “High level, your immune system is very complex and it has a bunch of different cells involved in fighting infection. The allergy cells are still part of the family of the immune system.” But, she says: “When they are activated, they do not activate a fever response.”

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If you experience a fever, you may likely be dealing with a viral infection

Because many of the symptoms between allergies and viral infection seem similar, Burke says it can easily be confusing to differentiate which response your body is experiencing. Fever can be an easy indicator to help you distinguish that you are dealing with a viral or bacterial infection, instead of allergies. “I think this is a deciding factor, or early on with COVID-19, that if you have a runny nose or red eyes and a fever its more likely infection. If you don’t have a fever, it could possibly be allergic,” she explains.

Another clear indicator between differentiating allergies and infection is dealing with itchiness and sneezing. “Itchiness and sneezing are more allergies, and the infection-fighting response releases [other symptoms] that trigger fever.”

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Sinus infections could lead to a fever

The one caveat Burke explains in all of this is if a person is dealing with a sinus infection. “Some people who can get really bad allergies that could get a sinus infection and their sinuses can’t drain, so they may get a secondary sinus infection and the allergies triggered it and gave them a fever.”

According to the American College of Allergy, Asthma and Immunology, sinus infections are bacterial that can result in symptoms such as headache or facial pain, runny nose and nasal congestion, coughing, and a fever. However, given that a fever is triggered due to a bacterial infection, it still answers the question of whether allergies alone can cause a fever, and the answer is no.

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