Tonsillitis is more commonly seen in children, but it can occur in adults, too. We explain the symptoms, treatment options, and when to seek help for this condition. Swollen tonsil on one side can be due to many underlying health conditions. Swollen and inflamed tonsil is common in children aged two to fifteen, but it can affect adults too. There are numerous reasons why you may be having one swollen tonsil. This condition is contagious and can be caused by a variety of common viruses and bacteria, such as streptococcal bacteria, which causes. Sore throats can result in pain, a scratchy sensation, hoarseness, and burning when you swallow. A persistent sore throat can recur multiple times, or it can be long term (chronic). A sore throat and swollen tonsils are the symptoms of a condition called tonsillitis3. When these harmful substances become trapped on the tonsils, they cannot travel down into the throat. Medline plus notes that the sore throat and swollen tonsils associated with tonsillitis usually go away within two to three days after the treatment begins3. Swollen tonsils, also called tonsillitis, can be caused by a number of things. Most commonly, tonsils swell due to a bacterial or viral infection. Though its not as common in adults, strep throat is a bacterial infection that can cause swollen tonsils and inflammation, says dr.