Canker Sores in Children: Causes and What Helps

Canker sores in children have the same drivers as in adults — a bitten cheek, a toothbrush scraping the gum, a stressful stretch at school, or low iron, folate or B-12. StatPearls places the first appearance of recurrent aphthous stomatitis in childhood or adolescence, so a child who starts getting them is following the usual timeline, not an unusual one.

What sets them off at this age

• Small injuries. Erupting teeth, a fall, a toy or pencil chewed, a cheek caught between molars. Children collect more mouth trauma than adults do.
• Braces and appliances. A bracket or wire that rubs the same millimeter of lining will keep producing ulcers in the same spot until it is adjusted.
• A narrow diet. Selective eating is common, and it is the route by which iron, folate and B-12 fall low enough to matter.
• Stress and disrupted routine. New school, new sibling, a bad week of sleep.

A mouth ulcer in a child is not always a canker sore

This is the part worth slowing down on. The American Academy of Dermatology describes a first herpes simplex infection — which most people catch in childhood — as a burning mouth followed by painful sores on the tongue, gums, lips or throat, together with fever, sore throat, painful swallowing, swollen glands and general illness, lasting one to two weeks. That picture is a sick child with many sores, not a well child with one. Hand, foot and mouth disease produces a similar crop alongside a rash on the palms and soles. Both are infections. Canker sores are not, and the difference is laid out in canker sore vs cold sore.

Feeding through it

Offer cool or lukewarm, soft and unseasoned food while the ulcer is open — yogurt, eggs, oatmeal, smoothies. Skip citrus, tomato sauce, chips, salty snacks and anything served hot. Keep brushing, but around the sore rather than over it, with a soft brush. An alcohol-free rinse is fine; alcohol-containing mouthwash stings badly enough that most children refuse the second attempt.

Numbing products: read the label

MedlinePlus explicitly warns against using lidocaine numbing medicine in children. Ask a pediatrician or dentist before applying any anesthetic gel, and confirm both the product and the dose for your child’s age. Salt-water rinses only make sense once a child can reliably spit.

When to call

• Fever alongside the mouth sores
• Refusing to drink, or signs of dehydration
• Many ulcers at once, or ulcers plus a rash on the hands and feet
• A sore that has not healed after two weeks
• Repeat episodes more than two or three times a year, which is MedlinePlus’s threshold for looking further

This content is informational and does not replace pediatric or dental consultation, diagnosis or treatment. See also recurring canker sores causes and how to relieve canker sore pain.