Varicella Zoster (Chickenpox)
Acute Alphaherpesviral Vesicular Exanthematous Disease
Primary risk age: Unvaccinated preschool and school-aged children.
- Urgency
- Moderate
- Typical age
- Unvaccinated preschool and school-aged children.
- Body system
- Infectious & Parasitic
Typical course: Acute illness resolves within 7 to 10 days; all lesions crust over by day 6-7.
Reviewed against AAP · CDC · WHO · NHS guidance Last reviewed 2026-06-13
1. Summary & Pathophysiology
Acute Alphaherpesviral Vesicular Exanthematous Disease
Pathophysiology (Development Path)
VZV enters via the respiratory tract or direct contact, replicates in local lymphoid tissue, and enters the bloodstream. It targets the capillary endothelial cells in the epidermis, causing localized fluid accumulation and vesicle formation. The virus then travels up sensory nerves to establish lifelong latency in dorsal root ganglia.
Primary Causes & Etiology
Varicella-Zoster Virus (VZV - Human Herpesvirus 3).
2. Symptom Continuum
- Early Onset Signs
Low-grade fever, mild headache, malaise, and loss of appetite, followed within 24 hours by an intensely itchy rash.
- Progressive Phase
The rash starts as small red spots (macules) that quickly turn into raised bumps (papules), then fluid-filled blisters (vesicles) on a red base (described as "dewdrops on a rose petal"). The blisters break and form crusts.
- Severe Indicators
Widespread rash with hundreds of lesions covering the mouth, throat, and genitals. High fever, persistent vomiting, ataxia (loss of balance), or severe chest pain, suggesting complications.
3. Clinical Verification
Typically clinical diagnosis based on the unique appearance of lesions in various stages of development (macules, papules, vesicles, crusts present simultaneously). PCR of vesicle fluid can confirm VZV.
4. Care & Elements Plan
Primary Care Treatment Plan
Supportive care: manage fever and itching. Avoid aspirin due to Reye syndrome risk. Administer oral Acyclovir for high-risk cohorts (adolescents, children with chronic skin conditions).
Home Support Elements
Apply calamine lotion to the lesions. Give lukewarm baths with colloidal oatmeal. Keep fingernails short and clean to prevent scratching and secondary bacterial infection. Keep the child isolated until all lesions have crusted.
Generic Active Ingredients (No Brands)
- Acetaminophen (generic active ingredient for fever
- avoid ibuprofen as it increases invasive streptococcal skin infection risk)
- Acyclovir (active antiviral used in older or high-risk children).
Lists active elements only. Never administer self-designed therapies.
5. Doctor Critical Lines
Critical Thresholds: When to See a Doctor
Consult a doctor if the skin lesions become very red, swollen, or warm (secondary bacterial infection), if the child develops a high fever, or has trouble walking or breathing.
6. Vaccine & Prevention
Routine Prophylaxis (Prevention)
Post-exposure prophylaxis with varicella vaccine or varicella zoster immunoglobulin (VZIG) for high-risk exposed contacts.
Immunization Context
Prevented almost entirely by the Varicella vaccine series (doses given at 12-15 months and 4-6 years).
7. Timelines & Outlook
Active Timeline
Acute illness resolves within 7 to 10 days; all lesions crust over by day 6-7.
Expected Prognosis
Excellent in healthy children; symptoms are typically mild. Adolescents and adults are at higher risk for severe disease.
Potential Untreated Complications
Secondary bacterial skin infections (Staphylococcus aureus or Group A Streptococcus cellulitis), cerebellar ataxia, varicella pneumonia, and Reye syndrome.
More in Systemic Contagious Viral Exanthems
Severe Measles (Rubeola)
Highly Contagious Paramyxoviral Exanthematous Disease
Unvaccinated infants, young children, and adolescents.
Moderate Roseola Infantum (Sixth Disease)
Viral Exanthema Subitum
6 Months to 2 Years
Mild Erythema Infectiosum (Fifth Disease)
Parvovirus-Induced Exanthem
4 to 10 Years