Recurrent Mouth Ulcers and Canker Sores in Children

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A mouth ulcer is a sore that develops in the soft lining of the gums, tongue, inner cheeks, lips, or palate. Younger children often get these as part of a viral or bacterial infection. Older children will sometimes have recurrent mouth ulcers, the cause of which can be difficult to pinpoint.

Mouth ulcers in children can often be diagnosed by a pediatrician or dentist. But, there may be times when a specialist may be needed if a more serious underlying condition is suspected.

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Hand foot and mouth disease
Hand foot and mouth disease. DermNet / CC BY-NC-ND​

This article explores the different causes of mouth sores in younger and older children. It also explains how mouth sores are commonly treated and prevented.

Causes of Mouth Ulcers

There are various factors a pediatrician will consider when trying to narrow the causes of a mouth ulcer in children. These include the child's age, the appearance and duration of the sores, and any accompanying symptoms.

Younger children are susceptible to many viral and bacterial infections that cause mouth ulcers. Among them:

  • Herpes gingivostomatitis is caused by the same virus that causes cold sores. Children with herpes gingivostomatitis often have irritability, high fever, and painful ulcers on the gums and inside the mouth.
  • Hand foot and mouth disease is a viral illness caused by the Coxsackie virus. Children usually get small, red ulcers in the mouth as well as on the palms of the hands and soles of the feet. A rash may also appear on the legs and buttocks.
  • Herpangina is similar to hand foot and mouth disease, except that the ulcers are just inside the child's mouth. Herpangina is also caused by the Coxsackie virus.
  • Gingivitis is a common and mild form of gum disease that can cause mouth ulcers. It is usually caused by a bacterial infection.
  • Geographic tongue is a harmless condition caused by the loss of tiny, hairlike projections on the surface of the tongue (called papillae). It causes smooth, red patches on the top or side of the tongue. It is not usually painful, and no treatment is needed. The cause is unknown.


Common causes of mouth ulcers in younger children include herpes gingivostomatitis, hand foot and mouth disease, herpangina, gingivitis, and geographic tongue.

Recurrent Mouth Ulcers

Recurrent ulcers can be difficult to diagnose because there are many possible causes. Some are pretty straightforward, like mouth traumas caused by a dental appliance or habitually biting your cheek. Recurrence is likely until the underlying problem is not resolved.

By far the most common is recurrence is aphthous stomatitis (also known as canker sores). Food allergies and vitamin deficiencies are thought to increase the risk of canker sores in kids. In many cases, no cause will be found.

Another possible cause is the herpes simplex virus 1 (HSV-1), the virus associated with cold sores. While most people get cold sores on the lip, others may have them inside the lip. Recurrence is common with some people getting five to six outbreaks per year.

Recurrent mouth ulcers may also be the result of a systemic (whole-body) condition, such as:

  • Behcet's syndrome: A rare autoimmune disease that causes recurrent canker sores, genital ulcers, and eye lesions
  • Celiac disease (CD): An autoimmune disease affecting the small intestine caused by eating gluten (a cereal protein found in wheat, rye, and barley)
  • Cyclic neutropenia: A recurrent drop in a type of white blood cells called a neutrophil that can lead to mouth ulcers and fever
  • HIV: A sexually transmitted infection that damages the immune system
  • Inflammatory bowel disease (IBD): A group of diseases that cause chronic inflammation in the digestive tract
  • Periodic fever syndrome (PFAPA): A condition in which children get episodes of fever, canker sores, and sore throat every two to eight weeks.
  • Vitamin deficiencies: Including iron, folate, zinc, and vitamin B12 deficiency


The most common causes of recurrent mouth ulcers in children include aphthous ulcers (canker sores) and herpes simplex virus 1 (cold sores).


The treatment of mouth sores is mainly focused on relieving symptoms. This includes using over-the-counter pain killers with Tylenol (acetaminophen) or nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil (ibuprofen).

There are also medications that can coat the ulcers and make them less painful. These include dental pastes and liquid antacids like Maalox or Milk of Magnesia.

Topical anesthetics can help numb mouth pain. These include 2% viscous lidocaine and benzocaine preparations like Anbesol or Orajel Mouth-Aid.

Antiseptics such as Peridex (chlorhexidine gluconate) and Cepacol (cetyl peridium chloride) can also ease the pain when used as a mouthwash twice a day.

Prescription steroids are also sometimes used. This includes Kenalog-40 (0.1% triamcinolone acetonide), a steroid drug that can be mixed with dental paste and applied to the ulcer several times daily.


The treatment of mouth ulcers may involve over-the-counter pain killers, coating agents, topical anesthetics, antiseptic mouthwashes, and prescription topical steroids.


If your child has recurrent mouth ulcers, it often helps to keep a symptoms journal. This allows you to identify what may have triggered the outbreak. By identifying the possible triggers, you can avoid the foods or substances that place your child at risk.

When no trigger is found, a toothpaste or mouthwash containing triclosan may be helpful. Triclosan has antibacterial properties that may reduce the risk of recurrence in some children. Colgate Total toothpastes contain triclosan.

On the other hand, an additive used in many toothpastes and mouthwashes, called sodium lauryl sulfate (SLS), may trigger aphthous stomatitis in some. If your child is prone to recurrent mouth ulcers, choose SLS-free toothpastes like Biotene and Rembrandt's Canker Sore toothpaste.

Dry mouth can also increase the risk of canker sores. You can reduce the risk by ensuring your child sips water regularly. You can also allow them to chew sugar-free gum whenever their mouth is dry.


Triclosan-containing toothpastes and mouthwashes may reduce the risk of mouth ulcers. On the other hand, toothpastes and mouthwashes containing sodium lauryl sulfate may increase the risk of mouth ulcers and should be avoided. Dry mouth should also be avoided.


Mouth ulcers are common in younger and older children for many reasons. In younger kids, viral and bacterial infections like herpes gingivostomatitis, hand foot and mouth disease, and gingivitis are common causes. Older children often have recurrent mouth ulcers, most often due to aphthous stomatitis (canker sores) or herpes simplex virus 1 (cold sores).

Certain systemic diseases can also cause recurrent mouth ulcers in kids. These include celiac disease, inflammatory bowel disease, vitamin deficiencies, and periodic fever syndrome.

Mouth ulcers can be treated with over-the-counter pain killers, coating agents, topical anesthetics, antiseptic mouthwashes, and prescription topical steroids. The risk of mouth ulcers may be reduced by avoiding dry mouth and using triclosan-containing toothpastes or mouthwash. You can also keep a journal to identify which foods or substances trigger your child's mouth ulcers.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Chansaenroj J, Auphimai C, Puenpa J, et al. High prevalence of coxsackievirus A2 in children with herpangina in Thailand in 2015Virusdisease. 2017;28(1):111‐114. doi:10.1007/s13337-017-0366-8

  3. American Osteopathic College of Dermatology. Geographic tongue.

  4. Massachusetts Dental Society. Mouth sores.

  5. Altenburg A, El-Haj N, Micheli C, Puttkammer M, Abdel-Naser MB, Zouboulis CC. The treatment of chronic recurrent oral aphthous ulcers. Dtsch Arztebl Int. 2014;111(40):665–673. doi:10.3238/arztebl.2014.0665

By Vincent Iannelli, MD
 Vincent Iannelli, MD, is a board-certified pediatrician and fellow of the American Academy of Pediatrics. Dr. Iannelli has cared for children for more than 20 years.