Mouth Sores in Babies & Toddlers

Content reviewed against published AAP, AAP, NIH guidelines

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Mouth sores in babies and toddlers can appear as ulcers, blisters, or red spots on the gums, tongue, inner cheeks, lips, or palate. The most common causes include hand-foot-and-mouth disease (Coxsackie virus), herpetic gingivostomatitis (HSV-1), canker sores (aphthous ulcers), and minor trauma from biting or teething. Most mouth sores resolve on their own within 7-14 days, but they can cause significant pain and feeding difficulty.

Key takeaways

  • Mouth sores in babies and toddlers can appear as ulcers, blisters, or red spots on the gums, tongue, inner cheeks, lips, or palate.
  • Most common cause: Hand-foot-and-mouth disease (Coxsackie virus)
  • Emergency: Mouth sores in newborn under 6 weeks (possible neonatal herpes)
  • Home care: Offer cold fluids and soft, bland foods (yogurt, smoothies, mashed banana)

Possible Causes

Hand-foot-and-mouth disease (Coxsackie virus)common
Canker sores (aphthous ulcers)common
Minor trauma from biting, falls, or sharp foodcommon
Herpetic gingivostomatitis (primary HSV-1 infection)uncommon
Herpangina (Coxsackie virus — back of throat)uncommon
Viral stomatitis from other virusesuncommon
Stevens-Johnson syndrome (medication reaction)rare
Behcet disease or other autoimmune conditionsrare

When to Seek Help

Emergency — Call 911 or go to ER:

  • Mouth sores in newborn under 6 weeks (possible neonatal herpes)
  • Extensive blistering of lips and mouth with skin peeling (Stevens-Johnson syndrome)
  • Mouth sores with difficulty breathing or swallowing saliva
  • Signs of severe dehydration (lethargy, sunken fontanelle, no tears)

Urgent — See doctor today:

  • High fever (over 40°C/104°F) with extensive mouth ulcers
  • Inability to swallow fluids for more than 8 hours
  • Spreading facial sores with swelling around eyes
  • Mouth sores with bleeding that will not stop

Same-day appointment:

  • Multiple mouth sores with moderate feeding difficulty but still taking some fluids
  • First episode of suspected herpes gingivostomatitis (fever, swollen gums, multiple ulcers)
  • Mouth sore lasting more than 2 weeks without healing

Monitor at home:

  • Single canker sore with mild discomfort but normal feeding
  • Mild hand-foot-and-mouth disease with child drinking adequately
  • Traumatic mouth ulcer from a known injury, healing normally

By Age

0-6 months

Normal: Epstein pearls (small white cysts on gums/palate) are normal in newborns and resolve without treatment. Bohn nodules on gums are also benign.

Worry if: Vesicles or ulcers in a baby under 6 weeks (possible neonatal herpes — medical emergency). Multiple sores with high fever and poor feeding.

6-12 months

Normal: Small sores from teething or biting are common. Mild viral ulcers from hand-foot-and-mouth disease are common in this age group.

Worry if: Extensive ulceration with high fever, drooling, and feeding refusal lasting more than 3 days. Sores with bleeding gums (primary herpes).

1-3 years

Normal: Hand-foot-and-mouth disease is very common in toddlers, especially in daycare. Canker sores may begin to appear. Traumatic ulcers from falls or biting are frequent.

Worry if: Sores lasting more than 2 weeks, recurrent severe episodes, sores with skin rash and joint swelling, or inability to maintain hydration.

Home Care

  • Offer cold fluids and soft, bland foods (yogurt, smoothies, mashed banana)
  • Avoid acidic, salty, or spicy foods that irritate sores
  • Use age-appropriate pain relief (acetaminophen or ibuprofen for babies over 6 months)
  • Offer ice pops or cold teething rings to numb pain before feeding
  • Keep baby hydrated with frequent small sips of water or oral rehydration solution
  • For toddlers, a mix of equal parts liquid antacid and diphenhydramine (Benadryl) can be dabbed on sores (ask doctor first)
  • Do NOT use numbing gels with benzocaine in babies under 2 years (risk of methemoglobinemia)
  • Maintain gentle oral hygiene — soft damp cloth to wipe gums
  • Wash hands frequently to prevent spread of viral causes

Frequently asked questions

What causes mouth sores?
Hand-foot-and-mouth disease (Coxsackie virus) (common); Canker sores (aphthous ulcers) (common); Minor trauma from biting, falls, or sharp food (common); Herpetic gingivostomatitis (primary HSV-1 infection) (uncommon); Herpangina (Coxsackie virus — back of throat) (uncommon); Viral stomatitis from other viruses (uncommon); Stevens-Johnson syndrome (medication reaction) (rare); Behcet disease or other autoimmune conditions (rare)
When is this an emergency?
Mouth sores in newborn under 6 weeks (possible neonatal herpes). Extensive blistering of lips and mouth with skin peeling (Stevens-Johnson syndrome). Mouth sores with difficulty breathing or swallowing saliva. Signs of severe dehydration (lethargy, sunken fontanelle, no tears)
What can I do at home?
Offer cold fluids and soft, bland foods (yogurt, smoothies, mashed banana). Avoid acidic, salty, or spicy foods that irritate sores. Use age-appropriate pain relief (acetaminophen or ibuprofen for babies over 6 months). Offer ice pops or cold teething rings to numb pain before feeding. Keep baby hydrated with frequent small sips of water or oral rehydration solution. For toddlers, a mix of equal parts liquid antacid and diphenhydramine (Benadryl) can be dabbed on sores (ask doctor first). Do NOT use numbing gels with benzocaine in babies under 2 years (risk of methemoglobinemia). Maintain gentle oral hygiene — soft damp cloth to wipe gums. Wash hands frequently to prevent spread of viral causes
When should I call the doctor?
Multiple mouth sores with moderate feeding difficulty but still taking some fluids. First episode of suspected herpes gingivostomatitis (fever, swollen gums, multiple ulcers). Mouth sore lasting more than 2 weeks without healing

Sources

AAPAAPNIH

All content follows our editorial policy and is reviewed against published clinical guidelines.

2,705 evidence-based guides6 authoritative medical sources

Related Symptoms

thrushdroolingrefusing to eatsore throat

Bottom line

Most cases of mouth sores in babies are not emergencies. However, seek immediate care if mouth sores in newborn under 6 weeks (possible neonatal herpes).

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.