Wondering about cast care? Get the answers to common cast care questions, from keeping a cast clean and reducing swelling to knowing when to call the doctor.

By Mayo Clinic Staff

If your child breaks a bone, a cast can help support and protect the injury as it heals. Without proper care, however, a cast can't do its job. Understand the basics of cast care.

Casts are custom-made to fit and support injured limbs. There are two main types of casts:

  • Fiberglass casts. Fiberglass is a type of plastic that can be shaped. Fiberglass casts are typically lighter and more durable than are traditional plaster casts. Air circulates more freely inside a fiberglass cast.

    Also, X-rays penetrate fiberglass casts better than plaster casts. This is helpful if your child's doctor wants to use an X-ray to examine your child's bones while he or she is still wearing the cast. Fiberglass casts are available in different colors.

  • Plaster casts. Plaster casts are easier to mold for some uses than are fiberglass casts. Also, plaster casts are typically less expensive than fiberglass casts.

Swelling can cause your child's cast to feel tight and uncomfortable. To reduce swelling:

  • Elevate the affected area. For the first 24 to 72 hours after your child's cast is applied, use pillows to raise the cast above the level of your child's heart. If possible, keep the cast raised even while your child is asleep.
  • Keep moving. Encourage your child to frequently move the fingers or toes of his or her injured limb.
  • Apply ice. For the first 48 to 72 hours after your child's cast is applied, loosely wrap an ice pack covered in a thin towel around your child's cast. Apply ice to the cast — not the skin — at the area of the injury for 15 to 30 minutes every few hours or so. There's no need to apply the ice during sleep.

A cast can cause your child's underlying skin to feel itchy. To relieve itchy skin:

  • Turn a hair dryer on a cool setting and aim it under the cast
  • Ask your child's doctor about giving your child an over-the-counter antihistamine

Don't allow your child to stick objects, such as a coat hanger, inside the cast to scratch his or her skin. This could cause an injury or infection.

It depends on the type of cast. For example:

  • Plaster casts are meant to stay dry. If your child has a plaster cast over cloth wrapping, do what you can to keep the cast dry. During daily bathing, consider covering your child's cast in two layers of plastic, sealed with duct tape — or using another type of waterproof shield. Also, keep the cast outside of the shower or tub.
  • Fiberglass casts can usually get wet. If your child has a fiberglass cast that's lined with a water-repellent liner, it's probably OK for him or her to get the cast wet if the doctor approves.

    Keep in mind, though, that even a fiberglass cast can become uncomfortable and irritate your child's skin when wet. As with a plaster cast, consider covering your child's fiberglass cast in plastic or using a waterproof shield during daily bathing.

To dry any type of cast, use a hair dryer on a cool setting. Don't use a warm or hot setting, which could cause a burn. You might also try a vacuum cleaner hose because it will pull air through the cast and speed up the drying process.

To keep your child's cast in good condition:

  • Keep it clean. Keep dirt and sand away from the inside of your child's cast. Cover your child's cast while he or she is eating.
  • Skip lotions. Avoid placing powder, lotion or deodorant on or near the cast.
  • Leave adjustments to your child's doctor. Don't pull the padding out of your child's cast. Don't trim the cast or break off rough edges without first asking your child's doctor.

Contact your child's doctor immediately if your child:

  • Feels increasing pain and tightness in the injured limb
  • Feels numbness or tingling in the injured hand or foot
  • Feels burning or stinging under the cast
  • Develops excessive swelling below the cast
  • Can't move the toes or fingers of his or her injured limb or they become blue or cold
  • Develops a crack, soft spots or a foul odor in his or her cast or gets the cast soaking wet and doesn't dry it properly
  • Says the cast feels too tight or too loose
  • Develops red or raw skin around the cast
  • Develops a fever of 101 F (38.3 C) or higher

Caring for a child's cast isn't always easy. Remind your child that taking care of the cast will help minimize discomfort during the healing process.

April 10, 2015