Common cold
The cold or acute upper respiratory tract infection is a very common and widespread infection caused by viruses. If the natural function of the nose is impaired, viruses enter and multiply more easily in the nasal mucosa, causing an infection that we "colloquially" call the common cold. In most cases, the common cold is mild and lasts for a week or less, and is accompanied by symptoms such as runny and stuffy nose, sneezing, sore throat, cough, headache, and sometimes fever.