One of the main causes of sinus drainage is simply being alive. Every day, the human body produces several liters of sinus fluid and mucus, and all of that natural fluid has to go somewhere. In the case of sinus drainage, fluid from the nasal passages and sinuses drains into the back of the throat, where it is swallowed several times a minute. Ultimately, most normal sinus drainage is eliminated through the kidneys as part of a person's urine. However, abnormal types of sinus drainage can be caused by factors like bacterial infections, viral infections, allergens, acid reflux disease, irritating fumes, or dehydration.
Some people may experience sinus drainage in the form of a runny nose after eating spicy foods or inhaling an irritating odor. The mucus-producing glands in the nasal area react to such irritants by increasing their production of a watery fluid similar in texture to saliva. By flooding the affected area, the body hopes to flush out the irritants and reduce the inflammation they cause. This type of sinus drainage is usually thin and clear, flowing freely down the back of the throat or out of the nostrils. Once the irritant is gone, sinus drainage usually returns to normal.
Another cause of abnormal sinus drainage can be a bacterial or viral infection, most likely a cold or flu. The amount of infected sinus fluid overwhelms the natural drainage system, causing it to pool in the nasal passages and become thicker. This thicker mucus trapped in a dark, moist environment is an ideal feeding ground for bacteria, which in turn causes discoloration and a foul odor. Infected mucus slowly drains into the throat and upper chest, creating even more opportunities for bacterial or viral growth. Cold and flu medications often contain an ingredient that chemically interacts with mucus, thinning it to improve drainage. Sinus medications also try to reduce the inflammation of the sinus passages, which in turn creates better drainage.
Sometimes the body reacts to dehydration by limiting the amount of fluid available to the mucus-producing glands. If a person has gone several hours without replenishing their water levels, the result could be abnormal sinus drainage. Some people may associate this runny nose with the onset of a cold or allergy, but it's actually a signal to rehydrate. Proper hydration with fluids other than alcohol or caffeinated beverages should help reduce this type of sinus drainage.
Allergens like dust and pollen can also trigger abnormal sinus drainage. The nasal passages become irritated or inflamed in reaction to a known allergen, then begin to swell. The body's natural reaction is to produce more mucus to remove the irritant. Usually this excess fluid would be drained into the throat for removal, but the throat often swells during an allergic reaction. The excess fluid becomes thicker and discolored by allergens, causing an unpleasant feeling of fullness in the sinus cavities. This form of sinus infection, or sinusitis, triggers a painful sinus headache and excessive sneezing or runny nose. Allergy medications that contain antihistamines may be more effective than decongestants for this type of allergy-induced sinus drainage.
Experts suggest that maintaining adequate hydration and avoiding exposure to known allergens can reduce the severity and duration of sinus drainage. Sufferers should also know the difference between sinus drainage triggered by infections and those triggered by allergens or irritants. Decongestant medications work better on infection-based sinus drainage, while antihistamines may produce better results with allergy-based incidents.