Your problem is known as post-nasal discharge, or post-nasal drip (PND). Most people describe the sensation as phlegm (or snot or mucus) dripping down from the back of the nose, or blocking the back of the nose or throat. To feel comfortable, they must clear the passages at regular intervals, in whatever way they can. Often, the throat becomes very sore, irritated and swollen.
It's usually a chronic problem, and some efforts to remedy it simply seem to make it worse.
Up to four pints of secretions is normal
It's quite normal to produce as much as four pints of clear thin mucus every day from the glands, which line the nose and sinuses (the sinuses are large cavities in the bones of the face that are normally filled with air and lined with glanular tissue). This may seem like an astonishing statistic, but most people are hardly aware of the process.
Tiny hair-like projections that line the surface of these cavities simply brush the mucus towards the throat and it's swallowed subconsciously. This process is an essential part of the body's defences, and the mucus carries foreign particles, such as bacteria and viruses, away to be destroyed in the gut.
But sometimes the secretions become abnormal, either excessive or thick. Then the person becomes much more aware of the whole procedure.
Excessive thin secretions
Many factors, especially those that increase the thickness of the lining of the nasal cavities and sinuses, can cause increased production of clear thin secretions.
These include: infections with respiratory viruses, such as cold and flu; allergies; exposure to cold air; spicy food and medication (including the contraceptive pill and, especially, drugs for high blood pressure).
Structural abnormalities, such as a deviated or irregular nasal septum, can also increase mucus production.
Excessive thick secretions
Mucus may become thick and copious in centrally heated homes in winter, in infections of the nose or sinuses (especially when a secondary bacterial infection sets in after a viral infection), and with allergies, particularly to dairy products.
Anything that interferes with the normal drainage of mucus from the nasal passages can also cause nasal discharge and post-nasal drip. A common example in children is when a foreign body, such as a tiny toy or bead, becomes stuck in their nose. More often in adults the problem is related to chronic inflammation and obstruction of the sinuses (known as chronic sinusitis) so that they're unable to drain properly.
This may be caused by infection or by nasal polyps, for example.
Treatment
Treatment of PND depends on the cause. You may need proper assessment by an ear, nose and throat specialist, although GPs often try simple remedies first.
Just by irrigating the nasal passageways several times a day with a specially prepared salt solution it may be possible to relieve a thickened or irritated nasal lining, for example.
If there's infection, antibiotics may help, but if the sinuses are chronically infected, surgery may be needed to allow them to drain properly.
Other drug treatments include:
- antihistamines - beware, these can make secretions even drier and thicker
- decongestants - these shouldn't be used long term
- anti-allergy drugs, such as sodium chromoglycate
- nasal steroids
Surgery
If medical treatments don't relieve symptoms, surgery may be necessary, especially if there are structural abnormalities such as a deviated nasal septum.
Treatment has been revolutionised by the use of tiny telescopes, known as fibre-optic endoscopes, and CT scans to examine the inside of the nasal cavities and identify where the problem lies.
These techniques are used in an operation called Functional Endoscopic Sinus Surgery (FESS), which determines the particular problem in individual patients and then removes thickened or diseased tissues to restore normal function.
This article was last medically reviewed by Dr Trisha Macnair in June 2008
