Are cold sores (Herpes Simplex Virus 1, HSV-1) contagious to toddlers?

Are Cold Sores Contagious to Toddlers?

Yes, cold sores (HSV-1) are highly contagious to toddlers and can cause serious infections in young children, particularly during primary infection. 1

Transmission Risk and Mechanisms

Cold sores spread to toddlers through direct contact with active lesions, saliva, or infected respiratory secretions. 2 The virus is particularly contagious from 1-2 days before visible lesions appear until all lesions are completely crusted over. 1

• Toddlers are at higher risk than adults because they are more likely to experience primary HSV-1 infection rather than reactivation, and primary infections in children tend to be more severe. 1
• Transmission commonly occurs through kissing, sharing utensils, cups, or toys contaminated with saliva from someone with active cold sores. 2
• Documented case reports confirm infant-to-family transmission, including a 15-month-old child who transmitted HSV to both maternal nipples during breastfeeding after being infected by an older sibling. 3

Clinical Severity in Toddlers

Primary HSV-1 infection in toddlers typically manifests as herpetic gingivostomatitis, which is significantly more severe than the recurrent cold sores seen in adults. 1

• Children present with fever, irritability, tender submandibular lymphadenopathy, and painful ulcers throughout the gingival, oral mucosa, and perioral areas. 1
• The infection can cause difficulty eating and drinking, leading to dehydration requiring medical intervention. 4
• Unlike adults where cold sores have no diagnostic significance for serious complications, children with recent labial herpes may be at risk for HSV encephalitis during primary infection. 1

Serious Complications

While rare, HSV-1 can cause life-threatening complications in young children, including encephalitis and disseminated disease, particularly in immunocompromised toddlers. 1

• HSV encephalitis in children aged 3 months to 16 years has been documented with primary infections. 1
• Immunocompromised children can develop severe local lesions or disseminated HSV with visceral involvement affecting the liver, adrenals, lungs, kidneys, spleen, and brain. 1

Critical Prevention Measures

Adults with active cold sores must avoid direct contact with toddlers until all lesions are completely crusted. 1

• Do not kiss toddlers when you have active cold sores or prodromal symptoms (tingling, burning before lesions appear). 2
• Avoid sharing eating utensils, cups, towels, or any items that contact the mouth. 2
• Practice rigorous hand hygiene, as the virus can be transmitted through contaminated hands touching the child's mouth or eyes. 2
• Be especially vigilant with infants under 6 months, as neonatal HSV can cause devastating multiorgan disease. 1

Treatment Considerations

If a toddler develops primary herpetic gingivostomatitis, oral acyclovir suspension is effective treatment. 4

• Dosing for children under 12 years: 20 mg/kg every 8 hours for 7-14 days. 5
• Early treatment shortens duration of symptoms and accelerates healing. 1, 4
• Severe cases with dehydration or inability to eat may require hospitalization for IV acyclovir and supportive care. 1

Common Pitfalls to Avoid

• Do not assume that absence of visible lesions means no contagion risk - viral shedding can occur 1-2 days before lesions appear. 1
• Do not dismiss mild symptoms in toddlers - even mild presentations can represent HSV infection and warrant evaluation. 1
• Recognize that HSV-1 seroprevalence increases progressively from childhood, with transmission often occurring through non-sexual contact in family settings. 2