A "sinus infection or "sinusitis" is an infection of the sinus cavities: those mucous-producing air filled cavities behind and adjacent to our nose and eyes. The most common cause of sinus infections are viruses. When we are well, the normal mucous that is produced in our sinuses exits via a tiny opening into our noses on a regular basis. Once in our nose, we blow or clean our noses as necessary. When we get a "cold" or a viral respiratory infection, the opening from the sinuses into our noses can get congested and obstructed with sticky mucous. This obstructed sinus can cause a sensation of pressure in our cheeks, teeth, around our nose, eyes, or forehead. Because the mucous can't exit via its normal route, the mucous begins to drain down the back of the throat. We have all experienced this sensation as needing to clear our throats; in it's mildest form, we have the occasional need to "ahem", clear our throat; at it's worst, the drainage triggers recurrent bouts of gagging and coughing. This is called "postnasal drip". At night while we sleep, the mucous drains with gravity. This can make us cough, disrupting sleep. Postnasal drip is one of the most common causes of cough in young adults.
Other symptoms that may occur with sinus congestion include sore throat, particularly on awakening, due to all the mucous that has collected. Mucous from the nose and throat may be discolored in the morning because it has accumulated and dried during sleep. Many times the color and thickness will clear once you are up and about. Ears can also feel blocked because the eustachian tubes get obstructed by the same congested tissue.
Interestingly, the sinuses can become obstructed towards the end of a cold---at a time when our nose is feeling less stuffy. Sometimes the only symptom we may experience is persistent postnasal drip causing a nagging cough following a cold.
Occasionally, bacteria can infect obstructed sinuses. The symptoms indicative of this can be somewhat similar to those of viral infections. However, a bacterial infection is suggested when sinus congestive symptoms are not improving or worsening after 7-10 days of cold symptoms. Mucous may become more persistently discolored-yellow, green, brown, or blood-tinged-and this discoloration doesn't clear during the day. Pain and tenderness over the cheeks, nose, teeth, or eyes may worsen and may be found to intensify when bending over. A loss of taste and smell may occur with worsening cough. Fever may develop with increasing weakness or fatigue. Like any illness, symptoms vary among individuals. However, if this is what you are experiencing, see your provider.
Fortunately, most of the time, congested sinuses clear on their own over 7-10 days. However, there are two things you can use to help this process along: decongestants and moisture- particularly in the form of sinus irrigation.