Viral Myositis: How to Care for Your Child

Myositis (my-oh-SY-tis) is inflammation (swelling and irritation) of the muscles. Kids and teens who have recently been sick with a virus (usually a cold or the flu) may get “viral” myositis. In some kids it may start 1 or 2 weeks after the virus. Kids complain of muscle pain, weakness, and sometimes swelling in the calves. After kids rest and drink liquids, their symptoms usually go away in a few days. Rarely, other problems with the muscles or kidneys can develop, so it is important to watch your child carefully over the next week.

• Offer your child lots of liquids to drink.

• Encourage your child to rest when weak or tired.

• If your child has pain, a medicine may help. You can give acetaminophen (such as Tylenol® or a store brand) exactly as directed.

• Do not give aspirin to your child or teen as it has been linked to a rare but serious illness called Reye syndrome.

• Follow the health care provider’s instructions about when your child can return to sports and active play.

Your child has:

• a new or higher fever

• muscle pain, swelling, or weakness that gets worse or spreads to new areas of the body

• muscle pain or weakness for more than a week

• new symptoms

Your child:

• has red or brown urine (pee)

• appears dehydrated; signs include dizziness, drowsiness, a dry or sticky mouth, sunken eyes, crying with few or no tears, or peeing less often

Why do muscle symptoms happen after some viruses? Health care providers aren't sure why muscle problems sometimes happen after someone has a virus. They believe it could be due to the way the body fights the virus or the virus getting into the muscles.

Which viruses are the most likely to cause muscle pain in children? Influenza A and Influenza B are the most common viruses that cause muscle pain. With the influenza viruses, the pain is almost always in the calves. The pain can be strong enough to cause a child not to walk.