Pharyngitis is inflammation of the throat, causing pain, soreness, and difficulty swallowing, often due to viral or bacterial infections. Throat infections are usually caused by a virus but may be caused by bacteria such as streptococcal bacteria. Symptoms include severe pain when swallowing and swollen, red tonsils. The diagnosis is based on an examination of the throat. If untreated, throat infection that is caused by bacteria may cause an abscess to form in the tonsils. Taking analgesics relieves pain; a streptococcal infection is treated with antibiotics. Sometimes the tonsils have to be surgically removed. Throat infections are usually caused by a virus but may be caused by bacteria such as streptococcal bacteria. Symptoms include severe pain when swallowing and swollen, red tonsils. The diagnosis is based on an examination of the throat. If untreated, throat infection that is caused by bacteria may cause an abscess to form in the tonsils. Learn how to tell the difference between a viral and a bacterial sore throat based on common signs and symptoms. Find out when to see a doctor and what treatments are available for each type of infection.