Pediatric Dentists Explain What Causes Canker Sores in Kids Press Services

What Causes Canker Sores in Kids? Understanding Triggers, Treatment, and Prevention

Needham, United States - January 16, 2026 / Chestnut Dental /

Pediatric Dentists Explain What Causes Canker Sores in Kids

Painful white or yellow sores inside a child’s mouth can quickly turn everyday activities like eating, drinking, and talking into uncomfortable experiences. These lesions, commonly known as Canker sores, develop on the soft tissues inside the mouth, including the inner cheeks, lips, tongue, or along the gum line.

Pediatric dental providers at Chestnut Dental in Franklin, Massachusetts, have noticed that canker sores are one of the most frequent oral health concerns in children; yet, many families find themselves puzzled about why they appear or how best to manage them.

Based on years of experience caring for children of all ages, the team recently shared educational insights to help parents better understand what causes canker sores in kids and how they can be managed.

Understanding Canker Sores

Clinically referred to as aphthous ulcers, canker sores typically appear as small, round or oval ulcers with a white or yellow center surrounded by a red border. While their size can vary, even small sores can be surprisingly painful. Discomfort is usually most intense during the first few days, particularly when the sore is irritated by acidic foods or brushing.

Fortunately, most canker sores heal on their own within one to two weeks without leaving scars. Unlike cold sores, they are not caused by a virus and do not appear on the outside of the lips. They are also not contagious, meaning they cannot spread from child to child through contact.

The exact cause of canker sores remains unclear, but dental and medical researchers have identified a number of contributing factors. Children of any age can develop them, though outbreaks are more common in teenagers and young adults. Studies also suggest that girls are more likely than boys to experience recurring sores, and family history appears to play a role.

Common Triggers That Can Lead to Mouth Sores

Several everyday factors can increase a child’s risk of developing canker sores. Minor injuries to the mouth (like cheek biting, brushing too aggressively, or irritation from orthodontic appliances) are among the most common triggers that can all damage soft tissue. Emotional stress and physical fatigue can contribute too. Busy school schedules, lack of sleep, and anxiety can weaken the body’s ability to heal, making sores more likely to appear.

Diet also plays an important role. Acidic foods such as citrus fruits and tomatoes, as well as spicy or salty snacks, can irritate sensitive areas inside the mouth. Underlying nutritional deficiencies are another important factor to consider. Vitamin B12, iron, folic acid, or zinc support immune function and tissue repair, so deficiencies may make the mouth more vulnerable to irritation and slow healing.

Managing Pain and Supporting Healing

Most canker sores heal on their own within seven to ten days, but parents can use over-the-counter pain relievers, topical gels, and protective pastes to ease irritation, especially during meals. Soft foods like yogurt, mashed vegetables, and scrambled eggs are less likely to aggravate sores while healing occurs.

If sores are unusually large, last longer than two weeks, or interfere with eating and drinking, professional evaluation may be necessary. In some cases, prescription rinses or topical medications can help speed recovery.

Reducing the Risk of Future Outbreaks

Although canker sores cannot always be prevented, certain steps may reduce how often they occur. Using a soft-bristled toothbrush, avoiding overly abrasive toothpaste, and choosing oral care products that are free of SLS (sodium lauryl sulfate, a foaming agent commonly found in toothpaste) can help protect sensitive tissues. Maintaining a balanced diet and minimizing highly acidic or spicy foods may also reduce irritation.

By sharing clear, evidence-informed guidance on what causes canker sores in kids, Chestnut Dental aims to support families with reliable oral health education. Understanding these common mouth sores empowers parents to recognize triggers early, ease discomfort, and promote healthier smiles as children grow.