Mouth Sores

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Viruses are tiny germs that can cause mouth sores as well as other illnesses. Some mouth sores are caused by the herpes virus. This is one of the germs that cause cold sores or fever blisters. It is not caused by sexual activity nor related to it. If your doctor has diagnosed your child with mouth sores, there are several important things you should know. 

Possible Signs and Symptoms

  • Fever that comes on suddenly
  • Child is very grouchy or has no energy
  • Small mouth sores and fluid-filled blisters that may be on the tongue and roof of the mouth
  • Swollen gums that may bleed
  • Severe mouth pain
  •  Will not eat or drink or poor appetite

How to Care for Your Child

Give your child lots of liquids that are low in acid

Mouth sores can last from 7 to 10 days. Keep your child home from school or childcare if he has a fever above 100 degrees F. Your child should be free of fever for 24 hours before going back to school.

  • For children under 1 year of age, give formula or Pedialyte.
  • For children over 1 year of age, give lots of liquids such as water, milk and popsicles (Picture 1). Avoid fruit juices such as orange juice. Juices that are high in acid may irritate the child’s mouth sores.
  • Give soft foods often, but don’t force your child to eat. Your child may have less appetite with the mouth sores, but it’s important to make sure the child keeps taking liquids.
  • Your doctor may prescribe medicines to soothe the mouth sores or reduce the swelling.
  • Your doctor may suggest Tylenol? or Motrin? for pain or fever. Do not give your child aspirin or products that contain aspirin.

How to Protect Others

Most viruses are spread by contact through droplets carried in the air from coughing or sneezing. Contact with saliva from the mouths of others can also spread the virus. 

To protect others:

  • Wash your hands after touching your child’s face or mouth.
  • Be sure to wash your child’s bottles, pacifier, eating utensils and cups in hot soapy water.
  • Don’t let other children use your child’s bottle or pacifier.
  • Soak any washable toys in a bleach solution for 2 minutes. (Mix 2 tablespoons of household bleach in a quart of water.)  Rinse well with plain water and air-dry.

When to Call the Doctor

Call your child’s doctor if your child:

  • Has a fever over 101 degrees F for more than 7 days.
  • Stops drinking liquids.
  • Gets even fussier.
  • Has any signs of dehydration (stops crying tears; has very little urine; has dry, cracked lips; acts very tired or lazy).

Other Helping Hands:

These other Helping Hands can help you care for your child.  Please ask for them if they have not been given to you: Temperature: Oral, Rectal and Axillary, HH-II-27, and Fever, HH-I-105.

If you have any questions, be sure to ask your doctor or nurse.

Mouth Sores (Viral) (PDF)

HH-I-197 9/98, Revised 9/11 Copyright 1998-2011, Nationwide Children’s Hospital