Stomatitis — inflammation of the lining of the mouth — is a common childhood condition that causes significant distress because it makes eating and drinking painful. In young children, it presents most commonly in two forms: herpetic stomatitis, caused by the herpes simplex virus, and oral candidiasis (thrush), caused by the fungus Candida albicans. Understanding the differences between the two, how each is managed, and when medical attention is needed helps parents respond appropriately to what can be an alarming presentation.
Healthbooq supports parents with evidence-based guidance on common childhood illnesses, including the symptoms, management, and warning signs associated with mouth infections in infants and toddlers.
Herpetic Stomatitis
Herpetic stomatitis is caused by the herpes simplex virus type 1 (HSV-1), which most children encounter for the first time in the first few years of life — often from a parent or carer who carries the virus asymptomatically. The primary infection produces a more pronounced illness than the cold sores that characterise subsequent reactivations.
The condition typically begins with fever, irritability, and a sore mouth. Within one to two days, painful ulcers appear on the gums, tongue, inner cheeks, lips, and palate. The ulcers are small, shallow, and surrounded by redness; they are extremely painful, and the child will typically refuse to eat or drink anything that contacts the sores. Drooling increases as the child avoids swallowing. Swollen lymph nodes in the neck are common. The acute phase lasts seven to ten days, with the ulcers healing without scarring.
The primary management priority is maintaining hydration. Cold, smooth foods and drinks — ice lollies, cold milk, yoghurt — are often tolerated better than warm or textured food. Paracetamol or ibuprofen manages pain and reduces fever; adequate analgesia given before offering drinks or food significantly improves the child's willingness to take fluids. Antiviral treatment with aciclovir, if started within the first seventy-two hours of the illness, can reduce the severity and duration; this is most relevant for immunocompromised children, for whom a GP prescription should be sought promptly. Signs of dehydration — dry mouth, reduced or absent urine, unusual lethargy — require prompt medical assessment, as some children become severely dehydrated from refusal to drink during herpetic stomatitis.
Oral Candidiasis (Thrush)
Oral thrush in infants presents as white or cream-coloured patches on the tongue, inner cheeks, gums, and palate. Unlike milk residue, which wipes away cleanly, thrush patches adhere to the underlying mucosa and bleed slightly if removal is attempted. The baby may be unsettled during feeding, though some infants with thrush feed without apparent discomfort.
Oral thrush is caused by Candida albicans, a fungus that is present in the mouth normally but proliferates when the balance of the oral microbiome is disrupted — as it may be after antibiotic treatment, in immunocompromised infants, or in breastfed infants where Candida is also present on the mother's nipples (which would cause maternal nipple pain).
Treatment is with antifungal medication — nystatin oral drops or miconazole oral gel (miconazole is preferred for infants over four months; nystatin is used in younger infants). The medication is applied directly to the affected areas in the mouth after feeds. Treatment is continued for forty-eight hours after the visible thrush has cleared to prevent recurrence. If the breastfeeding mother has nipple pain or signs of nipple thrush (redness, burning), both mother and baby need to be treated simultaneously to prevent reinfection.
Aphthous Ulcers
Recurrent aphthous ulcers (canker sores) — small, painful, round ulcers with a grey-white centre and red halo — occur in a minority of young children. They are not caused by infection and are not contagious. Their cause is not fully understood; triggers may include minor trauma (biting the cheek), stress, or nutritional deficiencies. They heal without treatment in one to two weeks. Topical anaesthetic gels provide symptomatic relief. Recurrent or unusually large or persistent ulcers warrant review by a GP to exclude underlying conditions.
Key Takeaways
Stomatitis — inflammation of the mouth's mucous membranes — in young children is most commonly caused by herpes simplex virus (herpetic stomatitis) or Candida albicans (oral thrush). The two conditions look and behave differently and require different treatment. Herpetic stomatitis presents as painful ulcers, fever, and refusal to eat; oral thrush as white patches that cannot be easily wiped away. Both are treatable and self-limiting, but adequate hydration during herpetic stomatitis is the most important management priority.
