Tonsillitis in Babies: Symptoms, Causes & When to See a Doctor

While it's possible, tonsilitis is very rare in babies under the age of 2. Most cases of baby tonsillitis occur between the ages of 1 and 4. Tonsilitis is an inflammation of the tonsils, two small glands at the back of the throat. It's usually caused by a bacterial infection, such as Streptococcus pyogenes (strep throat). If your baby is showing signs of tonsillitis, such as a fever, sore throat, difficulty swallowing, and swollen tonsils, it's important to take them to the doctor for evaluation.