Post-nasal drip (PND), also known as upper airway cough syndrome (UACS) or idiopathically as catarrh, occurs when excessive mucus is produced by the nasal mucosa. The excess mucus accumulates in the back of the nose, and eventually in the throat once it drips down the back of the throat. It can be caused by rhinitis, sinusitis, gastroesophageal reflux disease (GERD), or by a disorder of swallowing (such as an esophageal motility disorder). Other causes can be allergy, cold, flu, and side effects from medications.
However, some researchers argue that the flow of mucus down the back of the throat from the nasal cavity is a normal physiologic process that occurs in all healthy individuals. Some researchers challenge post-nasal drip as a syndrome and instead view it as a symptom, also taking into account variation across different societies. Furthermore, this rebuttal is reinforced because of the lack of an accepted definition, pathologic tissue changes, and available biochemical tests. PND is one of the most common etiologies for chronic cough, defined as a cough persisting beyond 8 weeks.
Post-nasal drip can be a cause of laryngeal inflammation and hyperresponsiveness, leading to symptoms of vocal cord dysfunction.
Causes
There are multiple causes of PND, which can be acute or chronic.
GERD
Gastroesophageal reflux disease (GERD) is often associated with a high prevalence of upper-respiratory symptoms similar to those of PND, such as coughing, throat clearing, hoarseness and change in voice. Reflux causes throat irritation, leading to a sensation of increased mucus in the throat, which is believed to aggravate and, in some cases, cause post-nasal drip. This persistent irritation can lead to increased mucus production as a result of pro-inflammatory pathways, producing symptoms of PND. The nasal mucosa can produce secretions, or mucus, that provides lubrication and protection for the nasal cavity. This mucus production is activated by the autonomic nervous system; specifically, cholinergic neuropeptides are responsible for increasing mucus production.
In some patients, mucus recirculation between natural and accessory ostia has been described as a mechanism that perpetuates post-nasal drip and chronic rhinosinusitis.
Diagnosis
Diagnosis of PND depends on both a detailed history and clinical examination to help determine its etiology. The history may begin with feelings of obstructed nasal breathing or "stuffy nose" with or without nasal discharge. If allergic rhinitis is suspected, a family history of allergic conditions as well as a personal history of other associated conditions such as food allergy, asthma, and atopic dermatitis can be evaluated. Decongestants such as pseudoephedrine can tighten blood vessels of the nasal mucosa and result in a decrease in mucus production.
One study has found that symptoms of postnasal drainage improved after 8 to 16 weeks of lansoprazole 30 mg taken twice daily regardless of the presence or absence of typical symptoms of GERD.
Other methods, such as drinking warm fluids and using saline nasal irrigation, may be useful for managing symptoms of PND but their exact efficacy is unclear in medical literature. Nevertheless, since postnasal drip is frequently associated with chronic rhinitis, the regular application of various saline solutions to the nasal cavity may be beneficial.
Epidemiology
Because PND is often characterized as a "symptom" rather than a separate condition, the exact incidence is unknown and varies by its etiology. Chronic rhinitis, which includes allergic and non-allergic rhinitis, can affect 30-40% of the population.