Canker sores are painful ulcers that form inside the mouth. Most people get their first canker sore during their teenage years. About 2–4 canker sores can develop at the same time.

Approximately 1 in 10 people develop canker sores. While anyone can develop canker sores, teenagers and women are more likely to experience them.

Young children can get canker sores. The sores can negatively affect eating, drinking, and sleeping.

Typically, canker sores can go away without medication. However, they can cause a lot of discomfort for younger people and may need treatment in some cases. Treatment can involve topical or oral medication to relieve pain and speed up healing.

This article will discuss canker sores in children, including the symptoms, causes, diagnosis, and treatment.

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Canker sores are noncontagious mouth ulcers. They can appear as white-reddish inflamed spots on the lips or inside the cheeks. Less commonly, canker sores may develop on the tongue, the gums, or the roof of the mouth.

While canker sores affect both adults and kids, most cases occur in the early years of life. According to a 2020 review, the peak period of onset for canker sores is between ages 10 and 19.

Doctors may also refer to canker sores as recurrent aphthous stomatitis (RAS). The course of the condition is similar in kids and adults.

Pain is the most common symptom of canker sores. They can also cause a burning or tingling sensation in the part of the mouth in which the sore is developing.

Once the canker sore is visible, it appears as a whitish spot.

The exact symptoms of canker sores vary based on their type. Three types of canker sores can occur in kids:

  • Minor canker sores: This is the most common type, accounting for about 80% of cases. Minor canker sores are usually a few millimeters in diameter and have slightly raised, reddish edges. They generally heal within 1–2 weeks and are unlikely to leave a scar.
  • Major canker sores: This type accounts for about 10% of cases. Major canker sores are 1–3 centimeters in diameter and affect the tissue of the gums. They can last for 6 weeks and may lead to scarring.
  • Herpetiform canker sores: This type accounts for approximately 5% of cases. The sores resemble pinhead sores that doctors might associate with herpes infection. However, these sores do not involve the herpes virus. Herpetiform canker sores can heal within 2 weeks and are unlikely to leave a scar.

Other serious symptoms include:

Children can get a canker sore once or rarely — for example, from biting their lip.

However, they can also experience recurrent canker sores, which may form 3–6 times per year, with 2–4 lesions developing at a time.

Experts do not know the exact cause of canker sores. However, the following factors can increase a person’s risk of developing one:

Some children may develop multiple canker sores as a symptom of an underlying condition or weakened immunity.

Doctors can diagnose canker sores by examining the lesions and taking a medical history.

They can perform other tests to potentially rule out underlying conditions that may be causing the canker sores. These conditions may also need medical attention.

Tests might involve:

  • Blood work: This may include taking a complete blood count and assessing the levels of folic acid, iron, ferritin, and vitamins.
  • Microbiological tests: These can help determine the cause of the canker sore. For example, healthcare professionals may use the Tzanck smear test or polymerase chain reaction assay to detect viruses, bacteria, or fungi.
  • Skin biopsy: A biopsy involves extracting a sample from the area around the ulcer and looking for changes to the tissue’s structure. This may be beneficial for diagnosing persistent canker sores, which are those lasting longer than 2 weeks.

Learn more about the difference between canker sores and cold sores.

Canker sores mostly heal on their own within a few days. However, several treatment options can help relieve pain and reduce the frequency of canker sores.

A doctor may prescribe medications for a child based on:

  • the child’s age and overall health status
  • the severity of the condition
  • the child’s tolerance or specific allergies to certain medications

Treatment can include:

  • Mouthwashes: Products containing triclosan and chlorhexidine can help prevent the growth of germs near the wound and reduce inflammation in the area.
  • Topical medications: Medications can be directly applied to the sore to reduce pain. Topicals are available in the form of sprays, gels, and creams.
  • Oral medications: Over-the-counter (OTC) medications such as acetaminophen (Tylenol) can help with pain management. Oral corticosteroids, such as prednisone (Rayos), can also reduce pain and promote faster healing in certain cases, such as when a child has significant, recurring canker sores.
  • Cauterization: This procedure uses laser therapy or silver nitrate solution to reduce pain and speed up healing.

Learn more about some home remedies for canker sores.

Approaches that a caregiver can take to ease pain include:

  • making a mixture of half a teaspoon of salt and 8 ounces of water, which a child can use to rinse their mouth
  • applying a paste of sodium bicarbonate directly to the ulcer
  • dabbing milk of magnesia directly on the ulcer using a cotton swab and making sure the child avoids eating and drinking for 30 minutes afterward
  • ensuring that the child avoids eating abrasive foods such as nuts and seeds
  • avoiding potentially irritating foods, such as acidic, salty, or spicy foods
  • ensuring that the child uses a soft toothbrush
  • encouraging the child to practice good hygiene and supervising them if necessary
  • giving the child OTC pain medications such as Tylenol

Canker sores are likely to resolve on their own. However, in some cases, children may need medical attention if:

  • the sore does not heal even after 2 weeks
  • the inflammation is severe
  • they have large or multiple sores
  • they experience other symptoms alongside the ulcer
  • sores recur very often

Canker sores are painful ulcers that are common among kids. In most cases, they go away on their own. However, some children develop multiple, frequent sores that can negatively affect their quality of life.

Several treatment options are available to reduce pain and the frequency of ulcers. A caregiver can take various approaches to help relieve symptoms, such as encouraging the child to practice good hygiene or giving the child OTC medications for pain.

Caregivers should take a child to a doctor if sores persist for a long time or cause severe symptoms.