inflammatory illness of the mucous membranes (mucous membrane) and underlying structures of the throat ( pharynx). Inflammation usually involves the nasopharynx, uvula, soft palate, and tonsils. The illness can be caused by bacteria, viruses, mycoplasmas, fungi, and parasites and by recognized diseases of uncertain causes. Infection by Streptococcus bacteria may be a complication arising from a common cold. The symptoms of streptococcal pharyngitis (commonly known as strep throat) are generally redness and swelling of the throat, a pustulant fluid on the tonsils or discharged from the mouth, extremely sore throat that is felt during swallowing, swelling of lymph nodes, and a slight fever; sometimes in children there are abdominal pain, nausea, headache, and irritability. Diagnosis is established by a detailed medical history and by physical examination; the cause of pharyngeal inflammation can be determined by throat culture. Usually only the symptoms can be treated—with throat lozenges to control sore throat and acetaminophen or aspirin to control fever. If a diagnosis of streptococcal infection is established by culture, appropriate antibiotic therapy, usually with penicillin, is instituted. Within approximately three days the fever leaves; the other symptoms may persist for another two to three days.

Viral pharyngitis infections also occur. They can produce raised whitish to yellow lesions in the pharynx that are surrounded by reddened tissue. They cause fever, headache, and sore throat that last for 4 to 14 days. Lymphatic tissue in the pharynx may also become involved.

A number of other infectious diseases may cause pharyngitis, including tuberculosis, syphilis, diphtheria, and meningitis.