Canker Sores in Kids: Remedies That Help
October 15, 2026
A canker sore is a small, shallow ulcer inside the mouth, usually on the inner cheek, lip, or tongue. It looks like a white or yellow spot with a red border, and it can make eating and talking miserable for a few days. I am Dr. Nina. The reassuring news I give parents: canker sores are not contagious, they are not caused by poor hygiene, and they heal on their own, usually within seven to ten days.
What causes them
Nobody knows exactly, but the usual triggers in kids are biting the cheek, a bump from a toothbrush, stress, and acidic or spicy foods irritating a small injury. Braces and orthodontic appliances can rub and start them too. Some children just get them more often than others, and that pattern often runs in families. They are different from cold sores, which appear on the outside of the lips and are contagious.
Remedies that actually help
You can't make a canker sore vanish overnight, but you can make your child much more comfortable. Stick to soft, cool foods and skip anything acidic, salty, or spicy until it heals. A warm salt-water rinse a few times a day can soothe the area for older kids who can spit reliably. An over-the-counter oral gel made for mouth sores can numb the spot before meals. For the worst days, something cold like a popsicle or ice chips can numb the area before eating. If your child gets sores constantly, try switching to a toothpaste without sodium lauryl sulfate, an ingredient that irritates some kids' mouths. And keep brushing gently. Good hygiene won't cure the sore, but it keeps the rest of the mouth healthy while it heals.
When to call us
Call our office at 212-561-5303 if a sore lasts longer than two weeks, if your child gets them very frequently, if the sores are unusually large, or if your child can't eat or drink comfortably. At a checkup we can make sure what you're seeing is really a canker sore and rule out anything else. We're at 54 Warren St, and we always go slowly and use kid-friendly words, so an exam is nothing to worry about.
Frequently Asked Questions
Are canker sores contagious?
No. Unlike cold sores, canker sores cannot spread to other people through kissing, sharing cups, or close contact.
Can my child go to school with a canker sore?
Yes. Since they aren't contagious, there's no reason to stay home. Just pack soft foods and let the teacher know eating might be uncomfortable.
Do canker sores mean my child has a vitamin deficiency?
Occasionally frequent sores are linked to low iron, B12, or folate, but most kids who get them have normal levels. Mention it at your child's checkup if the sores keep coming back.
Should I put anything on my toddler's canker sore?
For toddlers, the safest approach is soft foods and time. Most numbing gels aren't recommended for very young children, so check with us or your pediatrician first.