Eczema Herpeticum

Eczema herpeticum (EH), also called Kaposi varicelliform eruption, is a widespread infection of eczematous skin with Herpes Simplex Virus, the cold sore virus. Most cases are HSV type 1, occasionally type 2. It usually happens during a child’s first herpes infection, appearing 5–12 days after contact with an infected person. That person may have no visible cold sore, so a kiss from a relative can be the source. Recurrent episodes are unusual. EH is most common in infants and young children with Atopic Dermatitis. The eczema itself can be mild or severe, active or quiet (DermNet 2023). Children with AD appear to have weaker defences against herpes. Their skin is leaky (Skin Barrier Dysfunction), and the Th2 Immune Response lowers antimicrobial peptides. Early-onset, extensive or head-and-neck eczema and high IgE are linked with EH (Aronson et al., Pediatrics 2011).

Herpes Simplex Virus [causes] Eczema Herpeticum Eczema Herpeticum [part-of] Atopic Dermatitis Skin Barrier Dysfunction [worsens] Eczema Herpeticum Th2 Immune Response [worsens] Eczema Herpeticum

How it looks in a toddler. The signs are clusters of itchy, painful blisters, most often on the face and neck. They can also appear on normal skin or on old eczema patches. The blisters all look alike (monomorphic). They may have a central dimple (umbilication), be filled with clear or cloudy fluid, or look blood-stained (red, purple or black). They break down into small round “punched-out” erosions about 1–3 mm across, which can merge into larger crusted raw areas (NICE QS44; DermNet). New patches keep spreading for 7–10 days. The child is usually unwell, with fever, swollen glands, lethargy or distress. A useful clue for parents is that a toddler whose eczema normally itches now finds it sore. EH is easily mistaken for Infected Eczema or Impetigo, and the two can coexist: Staphylococcus aureus co-infection was found in 30.3% of 1,331 hospitalised children (Aronson 2011). NICE NG190 tells clinicians to consider EH whenever “infected eczema” is not improving on antibiotics.

Eczema Herpeticum [relates] Infected Eczema Eczema Herpeticum [relates] Impetigo Staphylococcus aureus [worsens] Eczema Herpeticum

Emergency red flags (same-day medical care)

Rapidly worsening, painful eczema; clusters of small blisters like early cold sores; uniform punched-out sores or crusted erosions; fever, lethargy or distress; any spots near the eyes. If eczema suddenly gets worse and is blistered, crusty or weeping, or the child has a high temperature or seems unwell, the NHS says to get an urgent GP appointment or call 111 (call 111 for under-5s). Untreated EH can spread to the eyes, brain, lungs and liver and can be fatal or cause blindness (NICE QS44; DermNet).

Treatment: aciclovir, without delay. NICE says children with suspected EH should start systemic Aciclovir (by mouth or injection) immediately and be referred for same-day specialist dermatological advice. Treatment should not wait for swab results. Eyelid or eye involvement also needs same-day ophthalmology (NICE QS44, from NICE CG57 recs 1.5.1.40–1.5.1.42). DermNet calls EH “one of the few dermatological emergencies”. It uses oral aciclovir (or valaciclovir) for 10–14 days or until the lesions heal, and switches to intravenous aciclovir if the child cannot take medicine by mouth or is getting worse. Swabs from the base of a fresh blister (PCR or viral culture) confirm the diagnosis. Bacterial swabs are taken too, and any secondary bacterial infection is treated with antibiotics. On steroid creams, DermNet notes they used to be avoided, but newer evidence (Steele et al., BJD 2023) suggests Topical Corticosteroids are safe and may be needed for active eczema. The paediatric cohort agrees: steroid creams on admission did not lengthen hospital stay (Aronson 2011).

Aciclovir [treats] Eczema Herpeticum NICE CG57 [regulates] Eczema Herpeticum Topical Corticosteroids [relates] Eczema Herpeticum

When to go to hospital, and what the paediatric data show. The guidance differs on where a child should be treated (see conflict below). The largest paediatric case series comes from Aronson et al. (Pediatrics 2011). It is a retrospective cohort of 1,331 children aged 2 months to 17 years admitted with EH to 42 US children’s hospitals between 2001 and 2010. There were no deaths. 3.8% needed intensive care and 3.9% had a bloodstream infection. Every day of delay in starting aciclovir lengthened the hospital stay: by 11% for a 1-day delay, by 41% if started on day 3, and by 98% if started on days 4–7. Before antivirals, reported mortality was 10–50%. So the lesson for parents is speed: a toddler with sudden painful, blistering eczema and fever should be seen that day, and if it is out of hours or the child is unwell, at an emergency department. The evidence here is graded moderate. The urgency and aciclovir are backed by consistent guidelines and large observational data, but only one small adult RCT (60 outpatients) has tested aciclovir against placebo (cited in Aronson 2011).

Conflict: [NICE CKS, n.d.] says “immediate hospital admission should be arranged if eczema herpeticum is suspected”. [NICE QS44 / CG57, 2013, updated 2023] says start systemic aciclovir immediately and refer for same-day specialist dermatological advice, without requiring admission. [DermNet, 2023] says prompt antiviral treatment “should eliminate the need for hospital admission”. Unresolved — add to open_questions.

Eczema Herpeticum [precedes] Aciclovir NICE [regulates] Eczema Herpeticum

Connections

• Atopic Dermatitis — emergency complication, source: NICE CG57
• Skin Barrier Dysfunction — impaired barrier and antimicrobial peptides raise viral spread risk, source: NHS
• Herpes Simplex Virus — causative agent (mostly HSV-1, often primary infection), source: DermNet 2023
• Aciclovir — immediate systemic treatment; each day of delay lengthens stay, source: NICE QS44; Aronson, Pediatrics 2011
• Infected Eczema — main differential and frequent co-existing state; consider EH when antibiotics fail, source: NICE NG190
• Staphylococcus aureus — bacterial co-infection in 30.3% of hospitalised children, source: Aronson 2011
• Impetigo — look-alike and possible secondary infection, source: DermNet
• Topical Corticosteroids — no longer contraindicated; not linked to longer stay, source: DermNet 2023; Aronson 2011
• NICE CG57 — recs 1.5.1.40–1.5.1.42 (aciclovir + same-day referral), source: NICE QS44
• Th2 Immune Response — lowers antimicrobial peptides, raising HSV susceptibility, source: Aronson 2011
• Adulterated Herbal Creams — hidden steroid can severely worsen it, source: Keane BMJ 1999
• Systemic Immunosuppressants — one ciclosporin child hospitalised with eczema herpeticum in TREAT, source: Flohr BJD 2023
• JAK Inhibitors — herpes infections in boxed warning, source: FDA labels 2026
• When to Refer — same-day referral / immediate admission, source: NICE CG57; NICE CKS
• Hyper-IgE Syndrome — DOCK8 deficiency predisposes to eczema herpeticum, source: Napolitano 2022