The common cold, or acute viral nasopharyngitis, was among humans a highly contagious viral infectious disease of the upper respiratory system. Symptons of the disease included sore throat, runny nose or nasal congestion, sneezing and cough, muscle aches or weakness, fatigue, headaches, and loss of appetite.
Because nasal passages were often congested, the speech of an individual suffering from a cold also could be affected. Odo once dryly remarked that his name sounded like someone with a bad head cold speaking the words "Oh, no!" (DS9 novel: The Siege)
The disease existed for a number of centuries, and for many years human medical science had been unable to cure the common cold. Even after humans discovered warp drive and began to move into the interstellar community there was still no cure other than methods used previously, such as a combination of fluids and plenty of rest. It would not be until the mid 24th century that a cure was finally discovered for the common cold. (ENT episode: "Sleeping Dogs", TOS episodes: "Plato's Stepchildren", "The Omega Glory", "The Lights of Zetar", TNG episode: "Datalore")