The Link Between Nasal Polyps, Asthma, and Allergies

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Nasal polyps are noncancerous growths that form in the walls of both the sinus and the nasal cavity inside the nose. They develop as part of an inflammatory response clinically referred to as “type 2 inflammation,” which occurs in severe cases of asthma and perennial allergic rhinitis (commonly known as chronic hay fever), among other conditions.

While smaller nasal polyps are asymptomatic, if they grow, a condition called chronic rhinosinusitis with nasal polyps (CRSwNP) arises. In these cases, the polyps block airways in the nose and sinus, increasing the chance of sinus infection and causing numerous other symptoms.  

While there are still questions about the exact nature of the links between nasal polyps, asthma, and perennial allergic rhinitis, it’s clear these conditions are closely related. CRSwNP most often occurs in allergic rhinitis cases, and it’s been linked to asthma—itself often an allergic reaction.

As such, treatment of these conditions is also intertwined. The medications or other treatments used to take on CRSwNP will also help with asthma and chronic allergy symptoms. In turn, managing asthma and perennial allergic rhinitis may sometimes reduce the formation or rate of growth of nasal polyps.

Given how closely these conditions are linked, it’s important to take a look at what they are, how they affect the body, and how they’re related.

Nasal Polyps and CRSwNP

According to most estimates, nasal polyps develop in 1 to 4% of the general population, and in addition to asthma and allergies, they can also arise due to bacterial infection as well as cystic fibrosis.

In the clinical environment, they’re most often encountered as a severe form of chronic rhinosinusitis (CRS)—long-standing inflammation of the sinus and nasal cavities­—in which nasal polyps start to develop (hence the name). This occurs in approximately 1 in 5 CRS patients.

Though people of all ages and sexes can develop CRSwNP, it most often occurs in middle-aged adults in their 30s and 40s.

Symptoms

Basically, CRSwNP arises when the nasal polyps start to block off nasal and sinus passages, leading to a build-up of mucus, as well as a range of other symptoms. When nasal polyps become advanced and severe, they’re actually visible; you’ll see shiny, gray-colored protrusions coming from the walls of your nostrils.

Beyond that, there are several other symptoms:

  • Runny nose and congestion
  • Postnasal drip (when secretions from the nose access the throat)
  • Loss of sense of smell and taste
  • Sinus pressure
  • Headache
  • Itchy eyes
  • Sneezing

To be considered CRSwNP, these symptoms must be present for at least 12 weeks.

Treatment

And what can doctors do about this condition? There are several options:

  • Nasal corticosteroid sprays: The most common approach involves using a corticosteroid nasal spray, most often Flonase (fluticasone propionate) to reduce the inflammation and shrink the polyps. This therapy may also require using saline solution to rinse the sinus and nasal cavity.
  • Corticosteroid medications: Often alongside nasal corticosteroid sprays, doctors will prescribe tablets or capsules of corticosteroids. You may be prescribed medications such as prednisone (sold under the names Rayos, Prednisone Intensol, and Deltasone, among others) or Cortef (hydrocortisone).
  • Surgery: If the polyps are unresponsive to drug treatment, a minimally-invasive, endoscopic surgery may be necessary to remove them. This is typically an outpatient procedure, sometimes performed while the patient is awake. 

As with some other conditions, the incidence and rate of progression of CRSwNP can be reduced by addressing the conditions that cause it, including asthma and allergic rhinitis.

Nasal Polyps and Type 2 Inflammation

Nasal polyps are typically a feature of a broader physiological response called type 2 inflammation, which can accompany both asthma and perennial allergic rhinitis.

This is essentially a biological chain reaction that’s set off when specialized immune cells—most notably eosinophils and mast cells, among others—flood the bloodstream. In turn, these cells stimulate the release of cytokines, a specialized protein involved in stimulating immune response.

It’s this signaling pathway that leads to the symptoms associated with CRSwNP and the development of nasal polyps. In cases of asthma, type 2 inflammation occurs primarily in the lungs (or lower respiratory tract), whereas this is primarily seen in the nasal passages and sinuses (or upper respiratory tract).

Notably, this inflammatory response has been found to affect the inner lining of the sinus and nasal passages, the epithelial layer, which is why sinus infection is prevalent among those with nasal polyps.

The nasal corticosteroid sprays used to manage CRSwNP—and by extension asthma and perennial allergic rhinitis—work to directly suppress this inflammatory response.   

 Nasal Polyps and Chronic Allergies

Perennial allergic rhinitis is a chronic allergic reaction most often caused by dust mites, though it can also be a response to dog or cat fur or other allergens. It’s the most common cause of CRSwNP, though the exact nature of this connection is still unknown.

What is clear, however, is that a majority of those who develop nasal polyps—an estimated 51 to 86%—have this chronic allergic condition. Further linking the two is the fact that the severity of CRSwNP symptoms tends to increase during periods of time when there are more allergens in the air.

Many of the symptoms of CRSwNP overlap with those of perennial rhinitis, which include:

  • Nasal discharge with clear or colored mucus
  • Loss of sense of smell or taste
  • Sinus infections
  • Headache
  • Facial pain due to sinus pressure

Alongside the formation of nasal polyps, it’s important to note that asthma often accompanies perennial allergic rhinitis, contributing to the breathing difficulties it’s associated with. No doubt this points to a common underlying inflammatory response.

Treating Perennial Allergic Rhinitis

One of the most effective ways to prevent nasal polyps is to effectively manage allergic rhinitis. Common treatment approaches include:

  • Allergen avoidance: This involves figuring out ways to reduce the presence of allergens in your environment. It may entail deep cleaning of all surfaces, regularly laundering bedding, opting for wood floors versus carpeting, or finding new homes for pets.
  • Medications: A number of medications can help with perennial allergic rhinitis, many of which are also indicated for CRSwNP. These include nasal or oral corticosteroids, antihistamines (such as Clarinex (desloratadine), Atarax or Vistaril (hydroxyzine), and sodium cromoglycate.
  • Allergen immunotherapy: Another approach to chronic allergic conditions involves exposing affected patients to increasing levels of allergens. Over time, this is expected to reduce the body’s inflammatory response, reducing the severity and frequency of symptoms.

Nasal Polyps and Asthma

There’s no doubt that asthma and nasal polyps are also closely related. Though other respiratory conditions can cause it, it’s most often itself an allergic reaction to pet dander, ragweed, and dust mites.

Among people with asthma, researchers estimate that anywhere from 26 to 56% have CRSwNP. When the two are combined, symptoms become significantly worse. Patients experience:

What is concerning about asthma is that, if untreated, severe cases—and certainly those associated with CRSwNP—can be fatal.

Aspirin Exacerbated Respiratory Disease (AERD)

Those with asthma and nasal polyps are prone to develop a condition called aspirin exacerbated respiratory disease (AERD). This is essentially a severe allergy to non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, and Aleve or Midol (naproxen) that leads to extreme shortness of breath, among other severe and potentially dangerous reactions.

If you’ve been prescribed this type of drug or are using an over-the-counter version and experience sudden breathing difficulties, stop taking the medications immediately and call for emergency medical help.

A Word From Verywell

Asthma, perennial allergic rhinitis, and CRSwNP are closely interlinked. While researchers are still piecing together the exact nature of their relationship, there’s no doubt that an understanding of type 2 inflammation will be a big part of the puzzle. This important work continues in an effort to improve outcomes for patients suffering from these diseases.

Conditions like asthma and chronic allergy, especially alongside nasal polyps, can be very challenging to take on. However, if you have these conditions, it’s important to remember that the medications and strategies employed today are more successful than ever in restoring health and quality-of-life.

You can breathe easier knowing that, with proper vigilance and appropriate care, these respiratory issues can’t stop you.

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8 Sources
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