Pharyngitis is caused by a variety of microorganisms. Most cases are caused by a virus, including the virus causing the common cold, flu (influenza virus), adenovirus, mononucleosis, HIV, and various others.

Bacterial causes include Group A streptococcus, which causes strep throat, in addition to corynebacterium, arcanobacterium, Neisseria gonorrhoeae, Chlamydia pneumoniae, and others. In up to 30% of cases, no organism is identified.

Most cases of pharyngitis occur during the colder months -- during respiratory disease season. It often spreads among family members.

Strep throat is a serious cause of pharyngitis. The complications of strep throat can include acute rheumatic fever, kidney dysfunction, and severe diseases such as bacteremia and streptococcal toxic shock syndrome.

• Sore throat
• Strep throat may be accompanied by fever, headache, and swollen lymph nodes in the neck
• Viral pharyngitis may be associated with runny nose and postnasal drip
• Severe cases may be accompanied by difficulty swallowing and, rarely, difficulty breathing
• Additional symptoms are dependent on the underlying microorganisms

The health care provider will perform an examination of the pharynx to look for drainage or coating. The skin, eyes, and neck lymph nodes may be examined.

If there is suspicion for strep throat a streptococcal screen and/or throat swab culture may be performed. Additional throat cultures or blood tests may be done depending on the suspected organism (e.g., mononucleosis, gonorrheae).

• The possible complications of strep throat include rheumatic fever, kidney inflammation, chorea, bacteremia (bloodstream infection) and, rarely, streptococcal shock syndrome
• In some severe forms of pharyngitis (e.g., severe mononucleosis-pharyngitis) the airway may become blocked.
• Peritonsillar abscess or retropharyngeal abscess are possible.