The commonest cause of pharyngitis is a viral infection. Sometimes it is due to a bacterial infection, or, more rarely, a chlamydial (see chlamydia) or mycoplasma infection.
Pharyngitis may also be caused by swallowing substances that scald, corrode, or scratch the lining of the throat. Inflammation of the pharynx can be aggravated by smoking or excessive consumption of alcohol.
Viral pharyngitis is the most common cause of a sore throat. Other symptoms associated with it may include discomfort when swallowing, fever, tender, swollen lymph nodes in the neck, and joint pain or muscle aches.
Usually a diagnosis is made by examining the throat. If a throat swab culture doesn't reveal a bacterial cause, then a viral infection is suspected.
There is no specific treatment for viral pharyngitis. Self-care measures include gargling with warm salt water (one half-teaspoon of salt in a glass of warm water) several times a day and taking anti-inflammatory drugs or medications, such as acetaminophen, to control fever. Excessive use of anti-inflammatory lozenges or sprays may actually make a sore throat worse.
It is important to avoid using antibiotics when a sore throat is due to a viral infection, as the antibiotics will not help, and using them in such a way contributes to bacteria becoming resistant to antibiotics.
In some cases of sore throat (for instance, in infectious mononucleosis), the lymph nodes in the neck may become extremely swollen, and anti-inflammatory drugs, such as prednisone, may be needed to ease breathing and swallowing.
The symptoms of viral pharyngitis usually go away within a week to 10 days.
Bacteria that can cause pharyngitis include Group A streptococcus, which leads to strep throat in some cases. Other, less-common bacteria that cause sore throats include corynebacterium, arcanobacterium, Neisseria gonorrhoeae, and Chlamydia pneumoniae. If strep-throat or some other form of bacterial pharyngitis is diagnosed, antibiotics may be prescribed.