The common cold is caused by a variety of viruses, but most common colds are mainly upper respiratory symptoms such as fever, cough, runny nose, sore throat, and sneezing.
The influenza virus is another virus that causes the common cold, but it is characterized by the sudden onset of systemic symptoms such as fever over 38°C, headache, joint pain, and muscle aches. As with common viral colds, symptoms such as sore throat, runny nose, and cough are also present.

Influenza viruses are more contagious than cold viruses and are especially prevalent during the winter months of November through March. Influenza also shares some of the symptoms of the common cold, but is stronger than the common cold.
Infants, the elderly, and pregnant women with low immunity can easily become seriously ill, and complications such as pneumonia and encephalopathy may occur.