Removal of adenoids in adults is rare, but it may be necessary for preventing infection or cancer. Adenoids are common in children and tend to disappear as people grow older. They are not commonly present in adults because they do not often factor into an adults' health.
Adenoids, along with the tonsils, are part of the immune system, which is important in fighting bacteria and germs that cause diseases. They are only present in children and begin growing from birth and become bigger by the time a child is 3 to 5 years of age. The NHS states that they start shrinking and disappearing by the time the child is 7 years old. They disappear because they have no role in the adult immune system.
Adenoids should only be removed if they have become swollen due to allergies or an infection caused by bacteria or a virus. In adults, adenoids could become cancerous and require removal. Patients with infectious mononucleosis may experience obstruction due to severe enlargement of the adenoids, as stated by the American Academy of Otalaryngology. If the adenoids are causing harm to one's health, a person will need to undergo an adenoidectomy: a quick surgical procedure to remove the adenoids.