Canker Sores in Children: Causes and Relief

Canker sores are shallow, painful ulcers that form inside the lips, cheeks, tongue, soft palate, or gum tissue. They are not contagious and usually heal on their own within one to two weeks. Minor injury, stress, illness, certain foods, nutritional deficiencies, or inflammatory conditions may contribute, especially when sores recur frequently.

What a typical canker sore looks like

A minor aphthous ulcer usually has a round or oval white-yellow center with a red border. It occurs on movable, non-keratinized tissue inside the mouth rather than as clustered blisters on the outer lip. Your child may feel tingling before the sore appears and pain with spicy, acidic, salty, or crunchy foods. One or a few small ulcers that heal without scarring fit the common pattern. Larger, numerous, or unusually persistent ulcers require a broader evaluation.

Common triggers and look-alikes

A cheek bite, sharp tooth, braces wire, hard food, or aggressive brushing can create a traumatic ulcer that resembles a canker sore. Viral infections can cause multiple mouth lesions with fever or rash. Recurrent aphthous ulcers may be associated with iron, folate, vitamin B12, or other deficiencies, celiac disease, inflammatory bowel disease, immune conditions, or medicine effects, although many children have no identifiable systemic cause. The pattern and accompanying symptoms guide whether medical testing is appropriate.

Comfort measures at home

Offer cool fluids and soft, bland foods; avoid citrus, spicy snacks, sharp chips, and products that sting. Maintain gentle brushing so plaque does not add inflammation. An age-appropriate pain reliever may be used only according to your child's medical guidance and label. Do not place aspirin directly on the ulcer, and avoid numbing products unless a clinician recommends them for that child's age. Orthodontic wax can protect a sore from a bracket or wire while the office addresses the source.

When treatment or testing is considered

A dentist or pediatrician may prescribe a topical anti-inflammatory medicine for significant or recurrent aphthous ulcers. Persistent mechanical irritation needs correction. Repeated episodes may prompt review of growth, diet, gastrointestinal symptoms, fever, skin or eye findings, medicines, family history, and laboratory testing. The goal is not to order broad tests for every single sore; it is to recognize a pattern that no longer behaves like an ordinary isolated ulcer.

When to contact the dental team sooner

Seek prompt care if your child cannot drink, shows dehydration, has high fever, widespread blisters or rash, eye symptoms, severe swelling, immune suppression, or ulcers lasting longer than about two weeks. Recurrent large sores, weight loss, diarrhea, or growth concerns deserve medical coordination.

Questions parents often ask

Are canker sores contagious?

No. Typical aphthous ulcers do not spread from person to person. Cold sores are caused by herpes simplex virus and follow a different pattern.

Can toothpaste cause canker sores?

Some people report fewer recurrences with toothpaste that does not contain sodium lauryl sulfate, but evidence and individual response vary. Ask before changing a child's fluoride product.

Can braces cause them?

Brackets and wires can create traumatic ulcers. Wax and adjustment can reduce rubbing, but true recurrent aphthous ulcers may occur independently of braces.

A practical next step

You don't have to figure this out alone, or at 11pm on your phone. Call us at (201) 345-3637 and we'll tell you what we actually see.

Sources

• American Academy of Pediatric Dentistry, Reference Manual of Pediatric Dentistry
• American Dental Association, MouthHealthy patient education
• National Institute of Dental and Craniofacial Research, oral-health information