Mouth Ulcers in Children: What to Do and When to Get Help

Quick answer

One or two small, shallow sores inside the lip or cheek, with no fever or other illness, may be simple aphthous ulcers (canker sores). They are not contagious and often heal within one to two weeks.¹ The immediate priorities are comfort and enough fluid.

Not every mouth sore is a canker sore. Fever, many sores, swollen or bleeding gums, blisters around the lips, a hand-or-foot rash, a painful tooth, a new medicine, or difficulty drinking changes what may be happening. A baby or child who cannot drink, is urinating much less, has no tears, is unusually sleepy or looks very unwell needs prompt medical assessment.

Do not put an adult numbing gel, crushed tablet, chemical, essential oil or strong home paste on a child’s mouth. Products and medicines have ingredient- and age-specific risks. Ask a pediatrician, pediatric dentist or pharmacist about the exact product before use.

First, look at the whole pattern

Before calling every white or painful spot an ulcer, note:

1. Where is it? Inside the cheek or lip, on the tongue or gum, on the hard/soft palate, or outside the mouth?
2. How many? One or two small sores, or many blisters/ulcers?
3. What else is present? Fever, sore throat, swollen or bleeding gums, lip crusts, rash on the hands/feet, eye symptoms, abdominal symptoms or sores elsewhere?
4. Can the child drink? Note urine or wet nappies, tears, mouth dryness, alertness and whether swallowing is too painful.
5. Was there an injury or local problem? Cheek bite, hot food, hard toothbrush, brace, sharp tooth, dental treatment or chemical exposure?
6. Is this new or recurrent? A first episode, a sore in the same place, or repeated episodes over months?
7. Did it follow a medicine? Record every prescription, over-the-counter medicine and supplement started recently.

A clear photo taken in good light can help a clinician understand how the lesion changed, but an image cannot reliably diagnose the cause by itself.

Common patterns—not a home diagnosis

Pattern	Clues that may fit	What to do
Simple aphthous ulcer (canker sore)	Usually one to three shallow sores inside the mouth; no fever or other illness; not on the outer lip	Support fluids and comfort; arrange review if it is not clearly healing by two weeks, is unusually large or keeps returning12
Minor injury or burn	Sore beside a bitten area, brace, sharp tooth, rough food or recent hot-food burn	Remove an avoidable irritant; ask a dentist about a sharp tooth/appliance; review if it persists after the suspected cause is removed2
Hand, foot and mouth disease (HFMD)	Fever or sore throat, painful mouth sores and a rash that can appear on hands, feet, buttocks, legs or arms	Focus on drinking and follow infection guidance; seek care if drinking is poor, fever lasts, symptoms are severe or not improving3
Primary herpes gingivostomatitis	Fever, many painful mouth sores or blisters, red/swollen gums, sores or crusts on lips/perioral skin, drooling or refusal to drink	Contact a clinician promptly, particularly for severe pain, dehydration, a very young child or weakened immunity; treatment decisions can be time-sensitive4
Dental source	One gum sore near a painful tooth, facial/gum swelling or pain with biting	Arrange dental or medical assessment; do not treat it as a nutritional ulcer
Medicine or wider inflammatory reaction	Mouth sores after a new medicine, or sores with eye/genital symptoms, widespread rash, blisters or skin peeling	Seek urgent medical assessment and take the medicine packaging/list; do not decide from this article whether to give another dose

This table is orientation, not diagnosis. Thrush, herpangina, immune conditions and other oral lesions can also look like white spots, blisters or ulcers. A clinician or dentist may need to examine the mouth and the rest of the child.

Helping a child drink and eat

Pain can reduce drinking before it meaningfully affects food intake. Hydration is therefore the first practical goal.

Fluids first

• Offer small, frequent sips of a fluid the child normally drinks and can safely swallow.
• Cool fluids may feel more comfortable than hot or acidic drinks.
• Do not force a straw if suction hurts; use the cup, spoon or other safe method the child tolerates.
• Keep track of urine or wet nappies and alertness rather than judging hydration only from appetite.

Ask a clinician what fluid is suitable if the child is an infant, has vomiting or diarrhoea, follows a medically restricted diet, or has another condition affecting hydration.

Foods that may sting less

If the child wants food, try a soft, cool or room-temperature option from their usual diet, such as:

• soft rice or khichdi;
• well-cooked dal or dalia;
• mashed vegetables;
• banana or another non-acidic soft fruit;
• plain curd, if normally tolerated; or
• another smooth, non-spicy family food.

The goal is comfort, not a special ulcer-curing diet. Do not pressure the child to finish a meal. Drinking matters more during a short period of painful eating.

Temporarily avoid a food if it clearly stings or scrapes, especially:

• chilli-heavy, very salty or very acidic foods;
• citrus juice, tamarind or sharp pickles;
• very hot foods or drinks; and
• hard, rough or sharp foods such as chips, hard toast or brittle snacks.

These foods do not need a permanent ban merely because an ulcer occurred.

Gentle mouth care

• Continue gentle cleaning with an age-appropriate soft toothbrush unless a clinician advises otherwise.
• An older child who can rinse and spit reliably may find a mild salt-water rinse comfortable. Do not give a rinse to a baby or a child who may swallow or choke on it.⁵
• Do not scrape, pop or pick the sore.
• If a brace, sharp edge or tooth repeatedly rubs the area, ask a dentist or orthodontic professional to assess it.

Pain medicines and mouth gels

Pain control may help a child drink, but the correct medicine and dose depend on age, weight, health conditions, current medicines and the product concentration. Ask a pediatrician or pharmacist about an age-appropriate oral pain medicine; this page does not provide a dose.

Do not assume a product is safe because it says “oral,” “mouth ulcer,” “teething,” “herbal” or “natural.” Check the active ingredient and age instructions.

The US FDA warns that over-the-counter benzocaine products should not be used for mouth or teething pain in children under two because of a rare, serious blood disorder, and that oral viscous lidocaine has caused severe harm after excess dosing or accidental ingestion in infants and young children.⁶⁷ These are US regulator warnings, not an India product list, but they show why an adult gel or copied dose is unsafe.

For any gel, rinse or medicine:

• show the exact package and ingredient list to a clinician or pharmacist;
• do not exceed the label or professional instruction;
• do not combine products with the same active ingredient; and
• keep the product out of children’s reach.

Do not start antibiotics, antivirals, steroids, vitamin tablets or iron merely because there is a mouth ulcer. Treatment depends on the diagnosis.

When to seek medical or dental care

Seek urgent care now

Seek urgent medical care if the child:

• has trouble breathing or cannot swallow saliva;
• is very drowsy, hard to wake, confused, unusually weak or looks seriously unwell;
• has signs of significant dehydration, such as very little urine, a very dry mouth, no tears or inability to keep drinking;
• has mouth sores with eye pain/redness, genital sores, a widespread blistering/peeling rash, or symptoms that began after a new medicine;
• may have a chemical burn or swallowed a harmful substance; or
• is a newborn with fever or blister-like lesions.

This is not a complete emergency checklist. Use local emergency services when a child has a life-threatening problem.

Contact a clinician promptly

Arrange prompt medical or dental advice for:

• painful sores that prevent normal drinking;
• many sores, fever, red/swollen/bleeding gums or bloody lip crusts;
• sores outside the mouth as well as inside;
• a hand/foot/body rash or another sign of infection;
• face or gum swelling, a painful tooth or one sore next to a tooth;
• worsening after the child had started to improve;
• a child younger than six months, or any child with weakened immunity; or
• an ulcer that began after a new medicine.

Arrange a non-urgent examination

Ask a pediatrician, pediatric dentist or appropriate clinician to examine:

• a lesion that is not clearly healing by two weeks;
• a very large, unusually shaped, bleeding or increasingly painful lesion;
• a sore that repeatedly returns in the same place; or
• recurrent episodes that interfere with drinking, eating, growth, school or sleep.

The American Academy of Pediatric Dentistry says persistent oral lesions need a working diagnosis and notes that biopsy may be considered when a soft-tissue lesion persists beyond two weeks despite removing a suspected cause or trying empirical treatment.² This does not mean every persistent child mouth ulcer needs a biopsy; it means it should not be repeatedly self-treated without examination.

Why do mouth ulcers keep coming back?

Recurrent aphthous ulcers often have no single obvious cause. Family tendency, local trauma and other triggers may contribute. Studies have found associations with some hematinic deficiencies and with conditions such as coeliac disease, but association does not prove that a specific deficiency caused one child’s ulcers.⁸⁹

Do not start iron, folate, vitamin B12, zinc or another supplement as a trial cure. Too much of some nutrients can be harmful, and supplementation can obscure the real question.

For recurrent or persistent ulcers, a clinician may ask about:

• frequency, size, duration, scarring and exact location;
• fever, growth, weight, appetite and the full diet;
• abdominal pain, chronic diarrhoea, blood in stool or other digestive symptoms;
• joint, eye, skin or genital symptoms;
• medicines and supplements;
• dental trauma, braces, sharp teeth, toothpaste or other local irritants;
• family history; and
• conditions or medicines that affect immunity.

That history and examination determine whether dental treatment, blood tests or evaluation for a wider condition is appropriate. A “simple check” is not automatically the same for every child.

Are mouth ulcers contagious?

Simple aphthous ulcers and sores caused by a bite or burn are not contagious.¹ Infections that produce mouth sores can spread. HFMD, for example, is contagious and often includes fever plus a hand/foot rash.³ Primary herpes infection can produce many mouth and gum lesions and can spread through contact with saliva or active lesions.⁴

Do not decide school attendance or utensil-sharing rules from the word “ulcer” alone. First identify the likely condition and follow the clinician, school and public-health advice that applies to it.

What about “garmi” and home remedies?

Families may call a mouth ulcer chhaala and explain it as “garmi.” That description may communicate the family’s experience, but it is not a diagnosis and cannot distinguish injury, aphthous ulcer, viral infection, dental disease, medicine reaction or a recurrent condition.

Avoid caustic, strongly acidic, very salty or unverified pastes and oils. They can irritate injured tissue, and ingredients or concentrations may be unknown. Comfort measures should not delay assessment when the child cannot drink, has fever/many lesions, is very young or unwell, or the lesion persists.

Questions parents ask

How long does a simple mouth ulcer take to heal?

A simple aphthous ulcer often heals in one to two weeks.¹ Other causes have different courses. Arrange an examination if the lesion is not clearly healing by two weeks, keeps worsening or has any warning feature.

My toddler will not eat. What matters most?

Fluids matter first. Offer small, frequent cool drinks and soft foods only if wanted. Watch urine/wet nappies, tears, mouth moisture and alertness. Seek prompt care if drinking is poor or you are concerned about dehydration.

Can I use a mouth-ulcer gel?

Do not choose from the product name alone. Ask a pediatrician, dentist or pharmacist to check the active ingredients, concentration and age instructions. Never use an adult product or copied dose for a baby or young child.

Is a vitamin deficiency the usual cause?

No conclusion can be made from the ulcer alone. Recurrent aphthous ulcers have associations with some deficiencies and systemic conditions, but many children do not have one identifiable cause.⁸⁹ Assessment should determine whether testing or supplementation is appropriate.

When could it be hand, foot and mouth disease?

HFMD commonly includes fever, painful mouth sores and a rash on the hands and feet; a rash can also appear elsewhere.³ A clinician can assess the pattern. Poor drinking and dehydration are the immediate concerns.

Should I see a pediatrician or a dentist?

A pediatrician is appropriate when there is fever, rash, dehydration, many lesions, medicine exposure or wider illness. A dentist is especially useful for a sharp tooth, brace/appliance problem, tooth pain, gum/face swelling, or a persistent local lesion. Either can direct the next step when the cause is unclear.

This article provides general information and does not replace individual medical advice.

Sources

Footnotes

1. American Academy of Pediatrics. Mouth Ulcers symptom guide. Accessed 13 September 2026. ↩ ↩² ↩³ ↩⁴

2. American Academy of Pediatric Dentistry. Management Considerations for Pediatric Oral Pathology. Latest revision 2025; Reference Manual 2026–2027. Accessed 13 September 2026. ↩ ↩² ↩³

3. US Centers for Disease Control and Prevention. HFMD Symptoms and Complications. Updated 7 May 2024. Accessed 13 September 2026. ↩ ↩² ↩³

4. Royal Children’s Hospital Melbourne. Clinical Practice Guideline: HSV Gingivostomatitis. Updated November 2025. Accessed 13 September 2026. ↩ ↩²

5. UK National Health Service. Mouth ulcers. Reviewed 11 March 2024. Accessed 13 September 2026. ↩

6. US Food and Drug Administration. FDA Letter Regarding Benzocaine. 21 May 2018. Accessed 13 September 2026. ↩

7. US Food and Drug Administration. Lidocaine Viscous: boxed warning—should not be used to treat teething pain. Safety communication dated 26 June 2014. Accessed 13 September 2026. ↩

8. Yılmaz S, Kırsaçlıoğlu CT, Şaylı TR. Celiac disease and hematological abnormalities in children with recurrent aphthous stomatitis. Pediatrics International. 2020;62(6):705–710. doi:10.1111/ped.14155. ↩ ↩²

9. Mousavi T, Jalali H, Moosazadeh M. Hematological parameters in patients with recurrent aphthous stomatitis: a systematic review and meta-analysis. BMC Oral Health. 2024;24:339. doi:10.1186/s12903-024-04072-5. ↩ ↩²