Loss of Smell: Is It Seasonal Allergies or Covid-19?

What are seasonal allergies, exactly?

Is a pack of tissues and antihistamines as essential as your phone and keys? You’re not alone. According to the Centers for Disease Control and Prevention, 20 million Americans—that’s approximately eight percent of the population—were diagnosed with hay fever (allergic rhinitis or seasonal allergies) in 2021.

At the same time, Covid-19 continues. As many of us have heard or learned personally, Covid symptoms can sometimes mimic those of seasonal allergies, colds, flus, and other illnesses that lead to loss of smell.

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Is your loss of smell a symptom of Covid-19?

It’s not always easy to tell—but, there are some important clues to keep in mind, says Alan Hirsch, MD, the neurological director of the Smell and Taste Treatment and Research Foundation in Chicago. That’s partly because as many as 700,000 to 1.6 million people in the United States who got Covid-19 may have lost their sense of smell for six months or longer. “With Covid-19, as many as 70 percent of people who lose smell also lose their sense of taste,” Dr. Hirsch tells The Healthy. This usually doesn’t happen with seasonal allergies, he says. “You can still taste salt, sour, sweet, and bitter with allergies, but not with Covid-19.”

There are other ways to know if your loss of smell is from Covid-19 or seasonal allergies—for one, it’s possible you’ll feel a lot worse with Covid, says Neeta Ogden, MD, an allergist and immunologist in Edison, New Jersey and a spokesperson for the American College of Allergy, Asthma, and Immunology (ACAAI). “With Covid-19, you will feel sick and have a lot more symptoms than if it’s simply seasonal allergies,” she says.

Symptoms more unique to Covid-19 can include:

• Fever

• Muscle aches

• Headache

• Digestive issues, like vomiting, diarrhea, and nausea

Symptoms that are typically unique to allergies:

• Itchy, watery eyes

• Itchy and runny or stuffy nose

Overlapping symptoms:

• Scratchy throat

• Congestion

• Cough

The most intense Covid-19 symptoms typically last up to 10 days, but allergy symptoms wax and wane throughout allergy season, she says. (Spring allergies begin in February and last until early summer in many parts of the U.S.)

If you suspect Covid-19, get tested or do an at-home test, Ogden suggests.

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Loss of smell from allergies

A runny or stuffy nose, sneezing, cough, shortness of breath, fatigue, and watery eyes are the most common seasonal allergy symptoms.

However, says Jill Poole, MD, allergist-immunologist with University of Nebraska Medical Center in Omaha, and a member of the Asthma and Allergy Foundation of America Medical Scientific Council: “Up to 50 percent of people with allergic rhinitis can experience smell disturbance with loss of smell of up to 25 percent. This is usually caused by nasal obstruction or inflammation resulting in blocking the abilities of odor particles to reach the olfactory epithelium, which is the specialized nasal tissue inside the nasal cavity involved with smell.”

There’s more, explains Payel Gupta, MD, assistant clinical professor at Mt. Sinai Medical Center in New York and SUNY Downstate Medical Center: histamines are chemicals released by your immune system when your body encounters an allergen. These histamines lead to inflammation that impacts the nerves inside the nose that help humans smell. “Allergies can also cause inflammation in your sinuses, the cavities in your skull,” Dr. Gupta says, “and this can cause these cavities to fill up with mucus and that can also affect your sense of smell.”

Neglect your allergies and you could develop a sinus infection, which causes a loss of smell too, Ogden says.

Why do seasonal allergies affect so many of us?

“People with allergies have an overactive immune system,” explains Dr. Gupta. “When their immune system detects an allergen, like pollen or dust mites, it overreacts by making antibodies called immunoglobulin E (IgE),” says Dr. Gupta, who is also a spokesperson for the American College of Allergy, Asthma, and Immunology, and the co-founder and chief medical officer for the telehealth allergy platform Cleared.

Those antibodies trigger the release of histamine, which causes the common seasonal allergy symptoms, including runny nose, congestion, and itchy watery eyes. These allergies are seasonal because the airborne pollen that causes them only circulates in the air during certain times of the year. February through August is typically prime time for these respiratory allergies, says Dr. Poole.

Why seasonal allergies happen—and only to some people

Seasonal allergies may be common, but most people don’t seek treatment. Only one in 10 Americans experience seasonal allergies serious enough to diagnose. What makes seasonal allergy sufferers different, says Poole, is often genetics. “Genetic predispositions play a role to some degree as it is more common to develop allergies if one or both parents have a history of allergies,” she says.

But if one or even both of your parents have allergies, you might still be sniffle-free…and vice-versa: if your parents have zero allergies, you can still have them. “Allergies can develop at any time during the lifespan. You can grow up with them and they can get better or you can develop them later in life,” Gupta says.

It’s very personal, which is what makes diagnosing seasonal allergies a challenge. However, a full medical history tracking your response during pollen season might provide clues. Allergists can also conduct skin allergy testing to confirm specific allergies, Poole adds.

If you have allergies and notice them getting worse over time, you’re not just imagining things, reports a February 2021 study in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

“For many of my patients, allergies are getting worse year after year,” Gupta says. “Climate change is causing a rise in temperatures and CO2 levels which has been shown to make pollen seasons longer and stronger every year. More pollen means more symptoms for allergy sufferers,” she explains, adding: “Essentially we are seeing an early spring and late fall season. So, even people with ‘seasonal’ allergies are experiencing symptoms almost year-round.”

How to prevent smell loss from allergies

If you think you may have seasonal allergies, Gupta suggests a wise first step is to book a test with an allergist to pinpoint what you might be allergic to and to determine if you could be a candidate for immunotherapy.

Allergy immunotherapy “coaches” the body to treat the underlying cause of environmental allergies using its immune system. By introducing small, and increasingly larger amounts of allergens into the body, the immune system gradually learns to tolerate them better. “These therapies target the specific allergy trigger that causes the immune system to overreact and may even reduce a person’s chances of getting new allergies,” she says. “There are two forms of FDA-approved allergy immunotherapy (AIT): either subcutaneous immunotherapy or allergy shots, that are given in a doctor’s office, or sublingual immunotherapy tablets, which are taken under the tongue at home,” she explains.

Over-the-counter medicines can also potentially tame allergy symptoms. A few options Drs. Poole and Gupta sometimes prescribe for their patients:

• Steroid nasal sprays
• Antihistamine nasal sprays
• Oral antihistamines
• Antihistamine eye drops

“Knowing how and when to use these medications is very important, so if you’re not feeling better, then it may be time to see an allergy specialist,” Gupta says.

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Lifestyle medications certainly can’t hurt either. Poole recommends these allergen avoidance measures:

• Close windows during peak pollen season
• Limit time outside during high airborne allergen exposure times, which tend to be late morning and early afternoon
• Shower, change clothes, and wash your face after being outside
• Wear a face mask when outside
• Try a neti pot or other nasal or sinus irrigation treatment
• Quit smoking, if you do

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When to seek medical care

Covid-19 virus is definitely still out there—so if you notice any loss of smell, Gupta suggests getting tested for Covid-19. If you test negative and believe your loss of smell might be due to allergies, check in with your allergist if your smell doesn’t return after a few weeks.

“Most smell loss is transient and resolved after four weeks, but the persistent loss of smell can lead to significant problems for the patient, including nutritional disturbance from lack of enjoyment of food and drink, social anxiety, and depression,” Dr. Poole says.

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