Symptoms typically peak on the second, third or fourth days of infection and last about 1 week. People are most infectious (likely to pass the cold onto others) during the first 24 hours of the illness, and they usually remain infectious for as long as the symptoms last. Up to 25% of people may have persistent symptoms, such as a nagging cough that can last for several weeks. For a small number of people, the congestion from a cold may allow another illness to take hold, such as a bacterial infection of the middle ear or the sinuses. Respiratory complications such as bronchitis or asthma can cause symptoms that last for a month or longer.