A viral disease, mononucleosis or the kissing disease, is also believed to be the cause of enlarged tonsils in people. This disease is observed in teenagers and young adults. Swollen tonsils with no sore throat can be caused due to food or airborne allergy. Pain and discomfort while swallowing, difficulty in speaking, etc., are the symptoms of this condition. On the other hand, other symptoms in toddlers and adults include ear infections, ear aches, and frequent sinus infections.