The common cold is a viral infection that primarily affects the upper respiratory system. Symptoms typically include a runny or stuffy nose, sore throat, cough, and sneezing. Many people also experience mild fatigue and a low-grade fever. In addition to these symptoms, some individuals may have a headache or body aches. Symptoms usually appear one to three days after exposure to the virus and can last for about a week. While the common cold is generally mild, it can sometimes lead to complications, especially in those with weakened immune systems.