Yes, Allergies Can Cause a Loss of Smell. So How Can You Be Sure It’s Not COVID-19?

Photo credit: Rohappy - Getty Images
Photo credit: Rohappy - Getty Images

Losing your sense of smell can be pretty nerve-racking, particularly because it’s a symptom of COVID-19—and a relatively common one, too.

A 2020 study published in the journal PLOS Medicine found that 78% of 567 people who had experienced a lost sense of smell or taste in the previous month tested positive for antibodies to SARS-CoV-2 (the novel coronavirus).

“I do think most people don’t necessarily recognize [a loss of smell] as a symptom of infection. They may just think it’s odd and not related,” Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security previously told Prevention. “But it seems to be a good indicator of COVID-19.”

However, a lost sense of smell (medically known as anosmia, which is often accompanied by a lost sense of taste, or ageusia) can be rooted in other issues, including upper respiratory tract infections like the common cold and, yes, even allergies.

As spring ramps up, you might feel confused if you have a sudden onset of symptoms, especially if they’re new to you. Ahead, doctors explain the link between allergies and a loss of smell in particular, plus what to do if you experience it.

Why do allergies cause a loss of smell?

It has a lot to do with how allergies work in the first place. When you come into contact with something you’re allergic to, it sets off a chain reaction that starts in your genes and is expressed by your immune system, according to the American Academy of Allergy Asthma & Immunology (AAAAI).

When your immune system detects an allergen, like pollen or grass, it overreacts by making antibodies called Immunoglobulin E (IgE). Those antibodies then travel to your cells, where they release chemicals called histamines—and those histamines set off typical allergy symptoms, like a stuffy nose, cough, and itchy, watery eyes.

Here’s where a loss of smell comes into play: The nerves that conduct your sense of smell to your brain are located within your nose, says Stanley Schwartz, M.D., Ph.D., division chief of Allergy-Immunology-Rheumatology at the University at Buffalo Jacobs School of Medicine and Biomedical Sciences. When you’re having an allergic reaction, those nerves can become inflamed and “that will cut off your sense of smell,” he explains.

Allergies can also cause sinusitis, an inflammation of your sinuses, i.e. the cavities in your skull that are located around your eyes and behind your nose. “Sinusitis can cause your sinuses to fill up with mucus,” Dr. Schwartz says, “and that can affect your ability to smell odors.”

Then, there’s the issue of just dealing with a stuffy nose due to allergies. “If you are very congested, you may notice decreased sense of smell,” says allergist and immunologist Scott Feldman, M.D., Ph.D., assistant professor of clinical medicine at the University of Pennsylvania Perelman School of Medicine. Uncontrolled inflammation in your sinuses due to intense allergies can also lead to nasal polyps, or growths on the lining of your nose and sinuses, which can also mess with your sense of smell, he says.

How to tell if your loss of smell is caused by allergies or COVID-19

COVID-19 is still spreading, so it’s important to consider that your lost sense of smell could be due to a coronavirus infection. But as positive cases decrease across the country and more people become fully vaccinated against the virus, it’s entirely possible that your loss of smell or taste could be stemming from allergies.

So, how can you tell the difference? First, a loss of smell due to allergies always happens along with nasal congestion, Dr. Schwartz points out. Plus, if allergies are the culprit, the loss of smell will come on gradually, says Kara Wada, M.D., an allergist and immunologist at The Ohio State University Wexner Medical Center. “Loss of smell from COVID is pretty sudden,” she says.

It’s important to keep your personal history with seasonal allergies in mind, too. If you’ve struggled with them in the past and develop a loss of smell around the same time as you usually develop allergy symptoms, “that’s worth considering,” Dr. Wada says.

If your loss of smell or taste happens in tandem with other notable coronavirus symptoms, especially a fever, you should be more suspicious that you might have COVID-19, says Richard Watkins, M.D., an infectious disease physician and professor of internal medicine at Northeast Ohio Medical University.

Can’t figure out what’s happening? It’s totally understandable, as the symptoms of COVID-19 and allergies tend to overlap. In this case, your doctor can help provide guidance. They’ll be able to get a detailed history of your symptoms and past experience with allergies. From there, they’ll likely recommend getting tested for COVID-19, just to be on the safe side.

What can you do if allergies have led to loss of smell or taste?

If you’ve tested negative for COVID-19 or you are pretty positive that your allergies are behind your loss of smell and taste because it’s happened before, there are a few things you can do to get relief.

✔️ Do your best to avoid your triggers.

This can be tricky if you’re allergic to outdoor allergens like pollen. But, if you can, Dr. Schwartz recommends staying inside with your air conditioner or an air purifier running when pollen counts are high in your area. Need to go out? Wear a face mask, even when you’re not going to be around others. This can help filter out irritating particles so you can breathe a bit easier and ideally avoid the onset of symptoms.

✔️ Try using a nasal spray.

A low-dose, regular use steroid nasal spray like fluticasone (Flonase) can help. “It doesn’t cure your allergies, but it reduces the inflammation that can lead to a loss of smell,” Dr. Schwartz says.

Saline sprays are another mild option that can be useful in helping to clear out gunk and allergens that could be lurking in your sinuses and nasal cavity, Dr. Wada says.

Azelastine (Astepro) is a nasal antihistamine that’s also “pretty effective” at combating allergy symptoms, says Dr. Schwartz. With these, “you don’t have to use it continuously—just use it on and off when you need it,” he explains, but you need a doctor’s prescription to get your hands on it.

✔️ Reach for an oral antihistamine.

While Dr. Feldman recommends using a nasal antihistamine or spray first, he says an antihistamine pill may help if you don’t find any relief from a spray solution. These medications block histamine to prevent allergy symptoms in the first place. Try Claritin or Zyrtec for non-drowsy options.

✔️ If all else fails, see your doctor.

If you’re struggling with a loss of smell or taste due to allergies and at-home solutions aren’t working, talk to your doctor. They will be able to offer up personalized suggestions to help you find relief.

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