As far back as the 19th century asthma experts have observed the link between asthma and nasal congestion. Recent studies seem to support this link. While studies are limited, they seem to show nasal congestion might be a trigger and a cause of asthma.
So let's investigate the evidence and see if we can come to a conclusion.
The two main causes of nasal congestion in asthmatics are:
- Sinusits: According to Mayo Clinic, it's swelling of the nasal sinuses that "interferes with drainage and causes mucus to build up." If it becomes persistent it may result in infections and other complications. If it lasts longer than 12 weeks it's called chronic sinusitis. About 15 percent of Americans have it, yet 70 percent of child asthmatics and 26 percent of adult asthmatics have it. It's often referred to as a cold that won't go away.
- Rhinitis: Nasal allergies or hay fever. If left untreated it can lead to sinusitis and otitis media. Studies show 75 percent of asthmatics have allergies. If rhinitis leads to sinusitis it's referred to as rhinosinusitis.
For simplicity purposes, we'll lump sinusitis and rhinitis together.
The Mayo Clinic lists the following symptoms:
- Difficult to breathe through nose
- Facial pain
- Nasal drainage
- Loss of sense of smell and/or taste
- Nasal obstruction
- Jaw or teeth pain
- Cough (may get worse at night
- Ear pain (otitis media?)
- Sore throat
According to Asthma for Dummies by Dr. William E. Berger, besides rhinitis, other causes of sinusitis are:
- Viruses (the common cold)
- Fungus (often results from prolonged systemic corticosteroid use)
- Nasal rebound (overuse of over the counter decongestants
- Nasal polyps
- Deviated nasal septums (the cartilage the separates the nostrils is crooked)
- Enlarged adenoids
So why is nasal congestion believed to be linked with asthma?
1. Observations: Many asthma experts over the years have observed asthmatics to have nasal congestion, deviated septums, polyps, etc. Likewise, as nasal symptoms are resolved asthma improves, and as nasal congestion worsens so does asthma.
2. Recent studies: They seem to prove what was observed.
So why would nasal congestion lead to asthma? There are a couple theories:
- Nasal drainage: This is often considered an asthma trigger
- Nasobronchial reflex: Irritants that stimulate the upper airway may result in inflammation of the lower airway
The second theory there I learned about through the book Emergency Medicine edited by Barry E. Brenner (NewYork, 1999, page 93). While I've read theories that propose inflammation of the upper airway may lead to inflammation of the lower just because they are connected, this theory provides a more scientific explanation.
Another theory proposes that if a person is exposed to something that causes airway inflammation (such as nasal drainage), and you're exposed to that something often enough so that the inflammation is ongoing, that inflammation may become permanent and result in hyperresponsive airways (asthma).