Common mouth sores in babies and toddlers
The soft tissues inside a baby's or toddler's mouth are especially prone to sores, and knowing which type it is helps you respond quickly and correctly.
Canker sores
Canker sores also occur in babies and toddlers: round or oval ulcers with a red border and a yellowish-white center. They are harmless but painful, and can interfere with nursing and eating.
Herpes simplex sores
Many small blisters grouped on the gums, tongue or palate, which break quickly into painful sores. The key difference: herpes sores come in clusters of small, shallow ulcers, whereas canker sores are usually single and deeper.
Oral thrush (candida)
White, cottage-cheese-like patches on the tongue, inner lips or gums. They can be wiped off gently but leave red, slightly bleeding tissue underneath. In babies, thrush can follow an imbalance of mouth flora or a course of antibiotics, and is sometimes accompanied by a yeast diaper rash.
Hand, foot and mouth disease (coxsackievirus)
Hand, foot and mouth disease is caused by enteroviruses, including coxsackievirus, and is most common in children under 5: fever, then small red spots that turn into painful blisters on the tongue and inside the mouth, sometimes with a rash on the palms and soles. It is highly contagious and spreads through nose and throat secretions, contaminated objects, blister fluid and stool (CDC). Most children recover in 7 to 10 days; the pediatrician makes the diagnosis, and should be called right away if the child is not drinking.
| Type of sore | What it looks like | Fever | Who to call |
|---|---|---|---|
| Canker sore | A single round ulcer, yellowish center and red border | Usually not | Pediatrician or dentist, if not healed within two weeks |
| First oral herpes | Clusters of blisters and shallow ulcers, swollen red gums | Yes, often high | Pediatrician |
| Oral thrush | White, cottage-cheese-like patches with red tissue underneath | Usually not | Pediatrician |
| Hand, foot and mouth | Blisters on the tongue and in the mouth, sometimes a rash on the palms and soles | Yes, often before the sores | Pediatrician |
What causes mouth sores in babies?
Mouth sores in young children have several possible causes, and the baby's developing immune system plays a central role. Viral infections, especially herpes, spread mainly through direct contact with a carrier or shared utensils.
Allergic or irritant reactions are another cause: some fruit acids, preservatives in baby food or detergent residue on pacifiers and bottles can irritate the mouth. The switch from milk to solid food introduces many new substances; noting when sores appear in relation to new foods helps identify a link.
Minor injuries are very common at an age when babies put everything in their mouths: a hard pacifier, a toy with sharp edges, or biting the tongue or cheek can cause a sore. During teething, the erupting tooth constantly rubs the gum and can make the area sore.
How to recognize oral herpes in children
A first oral herpes infection (herpetic gingivostomatitis) develops over a few days. It usually starts with fever, often high, marked irritability, refusal to eat and drink, and sometimes drooling. Small fluid-filled blisters then appear on the gums, tongue, palate or inner lips; they break quickly into many shallow ulcers with a bright red border that can merge into larger sore areas.
The most telling sign is inflamed gums: swollen, bright red and bleeding at the slightest touch (unlike ordinary gingivitis). Swollen, tender lymph nodes under the jaw and in the neck are also common, and some children have bad breath. A first oral herpes infection usually clears up in about 10 days, even without treatment. Keeping track of temperature and of how much the child eats and drinks helps when you speak to the doctor.
If you suspect oral herpes, contact the pediatrician, and go right away if the child stops drinking, shows signs of dehydration or the sores spread toward the eye.
Treating mouth sores in babies and toddlers
Care for mouth sores in young children combines symptom relief, treatment of the cause when needed and making sure the child keeps eating and, above all, drinking. Any product applied inside the mouth of a baby or toddler should be used only after an examination and on the advice of the pediatrician or dentist.
Do not use numbing gels or liquids (such as lidocaine or benzocaine) for teething pain or mouth sores in babies and toddlers unless a doctor tells you to: the U.S. Food and Drug Administration (FDA) warns of serious side effects in this age group. For relief, gently rub the gums with a clean finger or give a firm rubber teething ring (not frozen).
When oral herpes is diagnosed
When the pediatrician diagnoses oral herpes, he or she may prescribe an antiviral medicine that can speed recovery. The choice of treatment and dose is the doctor's alone.
10days
Usual recovery time from a first oral herpes infection
According to MedlinePlus (U.S. National Library of Medicine), a child with a first oral herpes infection usually recovers completely in about 10 days, even without treatment.
At home, the priority is fluids: cool, soft foods and drinks, and rest. For fever and pain relief, ask the pediatrician or pharmacist which medicine and dose suit your child's age and weight.
Oral thrush in babies is diagnosed and treated by the pediatrician, who decides whether an antifungal treatment is needed and which one. Never apply antifungal products to the nipple or give them to a baby without medical advice. If a nursing mother has signs of a yeast infection on her nipples, she should also see her doctor, to avoid passing the infection back and forth. Boiling pacifiers and bottle nipples helps treatment work and prevents a recurrence.
Canker sores in babies and toddlers: what helps?
Canker sores in toddlers usually heal on their own within one to two weeks. Protective gels can form a barrier over the sore and reduce friction with food, but they too should be given to a baby or toddler only on the advice of the pediatrician or dentist, who will explain how to apply them gently. A canker sore that has not healed within two weeks, large or recurring sores, or sores with fever should be shown to a doctor.
Diet matters while sores are active: offer soft, cool, bland foods and avoid acidic, spicy, salty or hot foods that increase pain. A sore mouth can make a child refuse food, so focus on fluids, smooth purées of non-acidic fruit and comfortable temperatures. Do not give honey to a baby under 12 months, in food, drinks or on a pacifier, because of the risk of botulism (CDC). If the child loses weight or shows signs of dehydration, call the pediatrician at once.
Examination, treatment plan and price quote
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During the consultation, Dr Haim Aseriel examines your teeth, explains all the options and gives you a transparent price quote, with no obligation. The clinic is at 12 HaTnufa Street, Jerusalem.
Tips to prevent mouth sores in babies
Prevention starts with gentle, age-appropriate mouth care from the first days of life: wipe the gums, tongue and palate with soft gauze or a silicone baby brush after feeds. This removes milk residue, lowers the risk of thrush and gets the baby used to daily mouth care before toothbrushing begins.
01
Pacifiers, nipples and utensils
Boil or sterilize them according to the manufacturer's instructions. Do not share pacifiers or spoons, and do not "clean" a pacifier in your own mouth: this passes germs and yeast from adult to baby. Replace cracked pacifiers and nipples.
02
Feeding
Breast milk contains antibodies that help protect the lining of the mouth. When solids start, introduce new foods gradually and watch for reactions; avoid very acidic, spicy or hard foods early on.
03
Teething periods
Gum massage with a clean finger, a firm rubber teething ring (not frozen) and extra care with mouth hygiene can ease these periods.
Parents should know the early warning signs: a change in gum color, an unpleasant smell or a bad taste in the mouth, or marked discomfort during feeds.
Tongue sores in children: when to see a doctor or a dentist?
Tongue and mouth sores in children need an assessment because their causes vary. Who to call depends on the situation:
- The pediatrician, right away: high fever, refusal to eat and drink, signs of dehydration (fewer wet diapers, unusual sleepiness), sores spreading toward the eye.
- The pediatrician: sores that have not healed within two weeks, suspected herpes, thrush or hand, foot and mouth disease.
- The dentist: a problem with the teeth or gums, a sore caused by an injury or a sharp tooth, or any question about a baby's oral hygiene; see also emergency dental care.
Oral herpes and hand, foot and mouth disease are contagious and spread easily in daycare. According to the CDC, a child with hand, foot and mouth disease can usually go back once there is no fever, the child feels well and is not drooling uncontrollably (CDC); in every case, the pediatrician decides when the child can return to daycare or kindergarten, in line with the daycare's rules.
At the clinic in Jerusalem, Dr Haim Aseriel examines the child's mouth, explains the findings to parents, in English if you prefer, and refers to the pediatrician when medical treatment is needed. To arrange an examination, including an urgent one, call the clinic during opening hours (Sun 8:00–19:00 · Mon 9:00–19:00 · Tue–Wed 9:00–21:00 · Thu 8:30–21:00 · Fri 8:00–14:00).
Mouth sores in babies: frequently asked questions
A first oral herpes infection in a child usually starts with fever, irritability and refusal to eat or drink. Small fluid-filled blisters then appear on the gums, tongue, palate or inside of the lips and turn into painful sores; the gums are often swollen and bleed easily. A child with these signs should be seen by the pediatrician.
A first oral herpes infection in a child usually clears up in about 10 days, even without treatment, according to MedlinePlus. The pediatrician may prescribe an antiviral medicine that can speed recovery. If the child stops eating and drinking, see a doctor right away because of the risk of dehydration.
A baby with mouth sores should be offered soft, cool, bland foods and drinks, avoiding acidic, spicy, salty or hot foods that make the pain worse. The most important thing is that the baby keeps drinking. Do not give honey to a baby under 12 months, not even on a pacifier, because of the risk of botulism.
Mouth sores in babies are most often caused by one of two common viruses: the herpes simplex virus, which causes a first oral herpes infection with fever and blisters on the gums and tongue, or coxsackieviruses (enteroviruses), which cause hand, foot and mouth disease, with mouth sores and sometimes a rash on the hands and feet. Both are contagious and are diagnosed and treated by the pediatrician.
Sources
- U.S. Food and Drug Administration, Safely Soothing Teething Pain in Infants and Children, 2024 – View source
- American Academy of Pediatrics (HealthyChildren.org), Thrush and Other Candida Infections, 2020 – View source
- MedlinePlus (U.S. National Library of Medicine), Herpetic stomatitis, 2025 – View source
- American Dental Association (MouthHealthy), Canker Sores – View source
- Centers for Disease Control and Prevention, Foods and Drinks to Avoid or Limit (Infant and Toddler Nutrition) – View source
- Centers for Disease Control and Prevention, About Hand, Foot, and Mouth Disease, 2024 – View source
