Mucous becomes think. Coughing, if present, can last two to three weeks. Green or yellow nasal secretions suggest a secondary bacterial bronchitis or sinusitis. Fever and more severe symptoms, especially muscle aches and cough, suggest the flu. If the disease comes quickly, is not too severe and resolves in one to two weeks, it is usually the common cold.
Allergies usually recur and can last for entire seasons.
Bacterial sinus infections are usually limited to the nose and usually will not resolve unless antibiotics are given. The key to treating a cold is to make your body comfortable while it fights the infection. Only your body's own defenses can fight off a cold. Antibiotics don't help, though they can treat or prevent secondary bacterial infections. Pain should be treated using Advil or Tylonal, especially for sore throat.