Canker Sores & Cold Sores: Causes, Symptoms, Treatment & When to See a Pediatric Dentist
Mouth sores are common in children and can cause significant discomfort, especially when eating, drinking, or brushing teeth. The two most frequent types are canker sores and cold sores, and while they may look similar, they have very different causes and care needs.
At Beverly Pediatric Dentistry in McLean, VA and Washington, DC, we help parents understand what type of sore their child may have, how to manage symptoms at home, and when professional care is needed.
What Are Canker Sores in Kids?
Canker sores (also called aphthous ulcers) are small, shallow sores that develop inside the mouth. They are not contagious and are not caused by a virus or bacteria.
They usually appear on soft tissues such as:
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Inner cheeks
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Inside lips
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Tongue
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Gums
Why do they happen?
The exact cause isn’t always clear, but they are commonly linked to:
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Minor mouth irritation (cheek biting, brushing trauma)
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Stress, fatigue, or illness
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Acidic or spicy foods
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Temporary immune changes
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Nutritional factors like low iron or B vitamins
What they look like:
They often appear as round or oval ulcers with a white or yellow center and a red border. Even small sores can feel very painful for children because the mouth is highly sensitive.
Most canker sores heal on their own within 7–14 days
What Are Cold Sores in Kids?
Cold sores are caused by the herpes simplex virus type 1 (HSV-1) and are contagious during active outbreaks.
They typically appear:
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On or around the lips
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At the edge of the mouth
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Sometimes near the nose or chin
How children get them:
Many children are exposed early in life through close contact. After the initial infection, the virus remains dormant in the body and can reactivate later.
Common triggers:
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Fever or illness
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Sun exposure
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Stress or fatigue
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Immune system changes
What they look like:
Cold sores often start with tingling or itching, followed by small fluid-filled blisters. These then break open, crust over, and heal within about 7–10 days.
Canker Sores vs Cold Sores (Simple Difference)
Canker Sores
Inside the mouth
Not contagious
Triggered by irritation
White/yellow ulcer
Cold Sores
Outside lips
Contagious (HSV-1)
Triggered by virus
Fluid-filled blisters
Understanding the difference helps parents respond correctly and avoid unnecessary concern.
Common Symptoms in Children
Regardless of type, mouth sores may cause:
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Mouth pain or sensitivity
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Refusal to eat certain foods
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Fussiness or irritability
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Drooling in younger children
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Avoiding brushing near the sore
Children often cannot describe the pain clearly, so behavior changes are usually the first sign.
How to Help Your Child at Home
Most mouth sores do not require treatment and will heal on their own. However, comfort care can make a big difference.
Helpful at-home care:
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Offer soft, cool foods (yogurt, smoothies, applesauce)
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Avoid citrus, salty, or spicy foods
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Encourage plenty of fluids
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Use a soft toothbrush to reduce irritation
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Rinse with mild salt water (older children only)
Pain relief:
Cold foods or chilled drinks can naturally soothe discomfort. In some cases, a pediatric dentist may recommend a safe topical treatment for more severe pain.
⚠️ Avoid medicated numbing gels unless directed by a dentist or physician.
Why Some Children Get Mouth Sores More Often
Some children are naturally more prone to recurring sores due to:
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Genetics (especially for canker sores)
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Frequent minor mouth injuries
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Stress, poor sleep, or illness
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Immune system fluctuations
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Nutritional deficiencies
Cold sores tend to recur in children already exposed to HSV-1, especially during times of stress or illness.
When to See a Pediatric Dentist
You should schedule an evaluation if:
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Sores last longer than 10–14 days
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Your child has frequent or recurring outbreaks
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Pain is affecting eating or drinking
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There is fever, swelling, or signs of infection
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You are unsure what type of sore it is
At Beverly Pediatric Dentistry, we can identify the cause, rule out more serious conditions, and recommend safe ways to relieve discomfort.
Other Conditions That May Look Similar
Some oral conditions can be mistaken for mouth sores, including:
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Minor injuries from biting or brushing
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Hand, foot, and mouth disease
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Gum inflammation (gingivitis)
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Dental infections or abscesses
If symptoms are unusual, spreading, or paired with fever, a professional exam is recommended.
Trusted Pediatric Dental Care in McLean & Washington, DC
For over 30 years, Beverly Pediatric Dentistry has provided gentle, expert care for children at every stage of development.
We focus on:
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Accurate diagnosis and clear guidance for parents
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Child-friendly, stress-free treatment
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Modern technology and gentle techniques
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A calm and supportive environment