Although tonsils are visible when you open your mouth wide, adenoids cannot be seen without a flexible lighted instrument.

Tonsils and adenoids are lymph nodes, similar to those found elsewhere in the body. Their job is to block airborne bacteria or viruses that enter the body through the mouth or nose, and to produce antibodies against infection.

Because they block invading bacteria and viruses, tonsils and adenoids sometimes become infected themselves. Frequent infections of the tonsils -- called tonsillitis -- can result in enlarged tonsils. People without tonsils can still get a sore throat, but symptoms may be worse in someone with tonsils. Adenoids, also, can become infected. Recurrent infections can lead to enlarged adenoids, which in turn can lead to breathing problems, especially at night.

Tonsillitis occurs most often in children, although adults can get it. Tonsils and adenoids play less of a role in fighting infection after about age 3. Tonsils tend to decrease in size after ages 8 to 12.

Other possible symptoms include tonsils that are redder than usual; tonsils that appear to have a white or yellow coating; painful swallowing; and a raspy voice because of the swelling, the AAO-HNS says. Bad breath without the other symptoms is quite common and does not indicate an infection. Tonsillitis may affect one or both tonsils. Call your child's health care provider if your child has a combination of these symptoms.

Other symptoms include a voice that sounds as though the nose is stuffy and sleep apnea, in which the breathing stops momentarily during sleep. Call your child's health care provider if your child has these symptoms. Without an accompanying sore throat and fever, however, these symptoms do not indicate an adenoid infection. Snoring, ear infections and mouth breathing may be caused by allergies. Noisy breathing may be caused by nasal congestion or asthma.

Antibiotics are used to treat infections caused by bacteria. In adults with mononucleosis, steroids may be prescribed to reduce the swelling of the tonsils and adenoids.

Although tonsillectomies were once nearly routine for children with tonsillitis, antibiotics are now the preferred treatment. Rapid strep tests allow doctors to immediately distinguish between bacterial infections (almost solely caused by streptococcus bacteria) and viral infections. The leading cause of sore throats is viral and should not be treated with antibiotics, the AAO-HNS says. Tonsils or adenoids may be removed, however, if a child has had at least three infections in one year and the tonsils or adenoids are causing breathing difficulties, such as snoring during sleep, sleep apnea or intermittent obstruction. Recurrent infections also may affect the eustachian tube, leading to ear infections and possibly hearing loss. A child who has had his or her tonsils or adenoids removed is not at greater risk for infection. Other parts of the body's immune system step in to provide protection.