Adenoids are masses of glandular tissue found in the back of the throat. They act to trap viruses and bacteria and are part of the immune system. They usually continue to grow until people reach the age of five or six, and remain the same size throughout a person’s life. The adenoids and tonsils are similar tissue located in the mouth, are closely linked, and often when something is wrong with the tonsils, it can also be seen in the adenoids, and vice versa. If both adenoids and tonsils are enlarged, it may make it more difficult to breathe or swallow.