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Cold sores are recurrent blisters caused by herpes simplex virus, usually around the lips. The virus remains in the body after initial infection.
Symptoms
Tingling or burning can precede grouped painful blisters that crust. First infection may cause fever, sore gums and poor intake.
The symptoms of cold sores can overlap with other childhood conditions. Age, timing, severity and effects on breathing, hydration, feeding, sleep and activity help a clinician decide what assessment is needed.
Causes
HSV spreads through contact with saliva or lesions. Illness, sunlight and stress can trigger recurrences.
Risk factors
A risk factor changes the likelihood of cold sores but cannot confirm a diagnosis. Children without recognised risk factors may still be affected, while many children with risk factors never develop the condition.
Diagnosis
Diagnosis is usually clinical. A swab may be used for severe, neonatal or unusual disease.
Online information cannot diagnose cold sores. A qualified professional may need to examine the child, review medicines and medical history, and interpret tests in context.
Treatment
Fluids, suitable pain relief and early prescribed antiviral treatment may be used in selected cases. Avoid kissing babies and sharing utensils during active sores.
Treatment for cold sores should match the child’s age, weight, severity and other health needs. Check medicine names, doses and suitability with a qualified professional, and never use another person’s prescription.
Home care
When a professional has said that mild cold sores can be managed at home, follow the care plan, support rest and fluids where appropriate, and note meaningful changes. Avoid unproven remedies and adult medicines.
Prevention
Not every case of cold sores can be prevented. Current vaccination, hand and respiratory hygiene, safe food handling, trigger reduction and correct use of prescribed preventive treatment can lower relevant risks.
Possible complications
Possible complications of cold sores depend on severity, duration and the child’s underlying health. Earlier review is appropriate when symptoms worsen, recovery stalls or normal drinking, breathing, sleep or activity is affected.
When to seek urgent medical care
Urgent care is needed for a newborn exposed or symptomatic, eye pain or redness, dehydration, widespread blisters, immune suppression or marked illness.
If a child with possible cold sores seems seriously unwell, seek urgent professional help even when every listed sign is not present. Call the local emergency number for collapse, unresponsiveness, severe breathing difficulty or another immediate threat to life.
Frequently asked questions
Can symptoms alone confirm the condition?
No. Symptoms associated with cold sores may have several causes, so examination or tests may be needed before treatment is chosen.
Can home care replace an assessment?
Home care may support a mild, assessed case of cold sores, but it cannot replace medical evaluation when warning signs, worsening symptoms or uncertainty are present.
When is follow-up appropriate?
Arrange follow-up for cold sores when symptoms persist, recur, interfere with normal function or fail to improve as expected. Seek urgent help sooner if warning signs appear.
Summary
Cold sores are recurrent blisters caused by herpes simplex virus, usually around the lips. The virus remains in the body after initial infection. Careful observation, evidence-based treatment and clear knowledge of urgent warning signs help families respond without trying to diagnose the child themselves.
References and further reading
These official health resources provide further guidance relevant to cold sores. Recommendations can change, and local professional advice should guide individual care.
OUR REVIEW PROMISE
Evidence-based, clearly reviewed.
Healthier Baby Today articles are reviewed for accuracy and updated as guidance changes.
Last updated: July 17, 2026
