A cast is a hard bandage that keeps part of the body from moving so it can heal.
Kids get casts after a broken bone, some surgeries, and other injuries.
Most casts are made of fiberglass. Fiberglass is a kind of plastic that can be molded to the body part. It dries hard. Some fiberglass casts are waterproof. Doctors only use this type of cast for some kinds of broken bones.
Another type of cast is made of plaster of paris. This white powder is mixed with water into a paste. The paste hardens when it's dried.
To put on the cast, a health care provider:
A fiberglass cast gets warm as it hardens. It cools in about 15 minutes.
If the cast is not waterproof, keep the cast and liner dry. A wet cast or liner can lead to a skin rash or infection.
Also:
If the cast is itchy:
Casts that don't have a special waterproof liner must be kept dry. It is better to take a bath than a shower because it is easier to keep the cast dry in a bath. To keep the cast dry while bathing:
If the cast or liner gets splashed, have a parent help you gently blow air into it from a hair dryer on the cool or fan-only setting. If some of the cast or liner goes under water or gets very wet, call your doctor.
Health care providers take off casts with a small electrical saw. The saw cuts through the cast material but stops before it touches the skin.
When the cast is off, the skin will probably look pale, dry, or flaky. The hair will look darker and the muscles will look smaller. This is normal and goes away within a few weeks.
Your parent should call the doctor if:
Take care of your cast so it stays in good condition. Sometimes your doctor will let you keep your cast as a souvenir — all you have to do is ask. You can look at it in the future, read what your friends wrote on it, and remember how you got better!
Casts help protect broken bones while they are healing. Find out how to care for a cast.
Reviewed by: Amy W. Anzilotti, MD
Date Reviewed: Mar 1, 2023