Earaches are extremely common in young children. Although they are not themselves infectious, they are caused by upper respiratory infections, which are infectious. These infections are spread through contact with respiratory secretions—through coughing and sneezing.
The ear aches because of inflammation of the middle ear, caused by fluid that builds up behind the eardrum. Kids often cry, pull on their ears, have a fever, act irritable, and are unable to hear well. In more severe cases, there can be nausea, vomiting, and diarrhea. The developing anatomy of the ear canal in children make some children more susceptible to infection because the ear canal does not drain fluids properly, allowing bacteria to grow. Most children will grow out of this problem.
To help prevent earaches, be sure everyone covers their mouth when they cough, and use a tissue once and throw it away immediately. Keeping toys clean is also a good preventive measure. Try to prevent children from sharing toys that they have put in their mouth, wash toys that children do put in their mouth, and try to teach good hand-washing habits.
Sometimes doctors give children antibiotics to cure these earaches, but they don't always work. Many of the organisms that cause the respiratory infections that lead to earaches are antibiotic resistant, and not all respiratory infections are bacterial (remember, antibiotics only help cure bacterial infections). Some children have chronic infections that only respond to surgery to insert a tube that drains fluid from the ear.