Canker sores, also called aphthous (AF-thiss) ulcers or mouth ulcers, are painful open sores that form in the lining of the mouth. The sores can be treated with medicines and usually go away in a week or two. Follow the instructions below to help your child feel better while the sores are healing.

• You can give medicine for pain if your health care provider says it's OK. Use these medicines exactly as directed:
  • acetaminophen (such as Tylenol® or a store brand)
  OR
  • ibuprofen (such as Advil®, Motrin®, or a store brand). Do not give ibuprofen to babies under 6 months old. 
• If the health care provider recommended a mouth rinse, use it as directed.
• Put recommended gels or creams on the sores as instructed.
• Offer your child plenty of water, ice pops, and cold milk. Cold liquids can help the mouth feel better.
• Don't offer acidic (citrus, tomatoes, etc.), spicy, salty, sharp, or crunchy foods. Also avoid hot drinks and sodas because they can make the pain worse.

Your child:

• does not want to eat or drink
• has trouble swallowing due to mouth pain
• has canker sores that don't go away in 2 weeks
• gets canker sores again
• has any of these signs of dehydration:
  • a dry or sticky mouth
  • peeing less
  • no tears when crying

Is a canker sore the same as a fever blister? No, canker sores are different from fever blisters (cold sores):

• Canker sores are white or gray sores surrounded by a red ring and happen inside the mouth. They are not contagious.
• Cold sores are small groups of tiny blisters that happen on the outside of the lips. They are caused by a virus and are contagious.

What causes a canker sore? Canker sores may happen from stress, lack of sleep, food allergies, or an injury (like biting the inside of the cheek). They also have been linked to low levels of folic acid, vitamin B12, zinc, and iron in the diet.

Can people sometimes tell they are about to get canker sores? Yes, some kids feel tingling or burning in the mouth 1 or 2 days before the canker sores appear. They also might not feel well, may have a fever, or may notice swollen glands in the neck.