What Causes Nasal Polyps?

What Causes Nasal Polyps?

Not being entirely understood, scientists and the medical community do not know why some people produce nasal polyps and others do not. Chronic inflammation in the lining of the sinuses and nose seems to start the polyp formation. It is suggested with some evidence that this is an immune system response unlike the immune system’s response for those not developing nasal polyps. The immune system for people who develop polyps seems to have different chemical markers in their mucous membranes promoting polyp growth.

Nasal polyps usually appear in middle-aged adults and the young, yet can develop at all ages.

What are nasal polyps? They are noncancerous fleshy and puffy enlargements of different sizes in the nose. They are brownish yellow, grayish, or can be pinkish, looking similar to grapes on a stalk that join to the nose lining, frequently in both nostrils. One side only being affected is not usual. Polyps also appear in the sinuses in the face and skull. They are located primarily in the sinuses close to the eyes and nose.


Nasal Polyps and Inflammation

Fluid accumulates in the mucous membranes triggered by inflammation. The cells being full of fluid are acted on by gravity causing the cells to progress, hanging down as polyps. They can appear as a cluster or as a single polyp. This condition is not a disease. No one seems to know why the inflammation happens. Several concepts have been proposed for what causes nasal polyps, with any combination of the following accounting for the development of polyps:

  • Inflammation is an immune response to infections such as viral, bacterial or fungal pathogens
  • Allergic reactions to environmental pollution
  • Genetic inheritance where DNA is passed from parents or ancestors increasing risk
  • Faulty immune system that attacks and irritates membranes causing inflammation creating polyps

Risk Considerations

Several conditions might encourage and intensify the conditions for what causes nasal polyps to grow. (Colon/uterine polyps have no connection with nasal polyps.)

  • Adult asthma (starts as an adult not in childhood)—and people (20-40%) with nasal polyps have asthma
  • Allergens (pet dander, pollen, trees, grasses, molds, smoke, dust) can cause symptoms that seem like a cold
  • Cystic Fibrosis individuals (25%) will be affected with nasal polyps
  • Inability to take Aspirin
  • Sinus infections
  • Respiratory infections

Polyps can be seen in the nostrils when they are large growths. They look like gelatin in the shape of elongated grapes. The nasal bridge (between eyes) can broaden in people with long established nasal polyps. This widening of the nasal bridge gives the appearance that the eyes are set apart farther.


Seek professional help for diagnosing your condition and for what causes nasal polyps.

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Wow – I didn’t know that nasal polyps were caused by things like allergies and asthma. I had a sinus infection and my doctor brought up something about nasal polyp possibilities, but I wasn’t sure what he was referring to. I thought of some more questions after I left the doctor’s office, so I looked them up and found this site, along with the answers I needed. Thanks!

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