Acute viral nasopharyngitis, often known as the common cold, is a viral infectious disease of the upper respiratory system (nose and throat). Symptoms include sneezing, sniffling, runny nose, nasal congestion; scratchy, sore, or phlegmy throat; coughing; headache; and tiredness. In severe and rare cases, symptoms of conjunctivitis (red, itchy, or watery eyes) may also accompany a cold. Those affected may also feel achy. Colds typically last five to seven days, with residual coughing and/or catarrh lasting up to one to two weeks. The common cold is the most common of all human diseases infecting adults at an average rate of 2–4 infections per year, and school-aged children as many as 12 times per year. Children and their parents or caretakers are at a higher risk, possibly due to the high population density of schools and because transmission to family members is highly efficient.
The common cold belongs to the upper respiratory tract infections. It is different from influenza, a more severe viral infection of the respiratory tract that shows the additional symptoms of rapidly rising fever, chills, and body and muscle aches. While the common cold itself is rarely life-threatening, its complications, such as pneumonia, can be.