How long does chickenpox last in children?

The active phase lasts 5 to 7 days, with new blisters appearing in waves. The last blisters crust over within 10 to 14 days. Your child can return to school once all lesions have crusted and no new blisters have appeared for at least 24 hours.

Can I give ibuprofen or aspirin for chickenpox?

No. Ibuprofen and aspirin (ASA) are contraindicated in chickenpox. Ibuprofen increases the risk of serious bacterial skin infections (necrotizing fasciitis). Aspirin can cause Reye syndrome, a serious neurological complication in children. Use only paracetamol (acetaminophen) for fever and pain, under medical guidance.

Is the chickenpox vaccine on Brazil's public schedule?

Yes. The varicella vaccine (VVZ) is on the SUS public schedule as a single dose at 15 months. The SBP/private schedule recommends 2 doses: 1st at 12 months and 2nd at 15 months. Two doses provide ~98% protection against severe chickenpox.

Can a vaccinated child still get chickenpox?

Yes, but in a much milder form called breakthrough varicella. It typically causes fewer than 50 lesions (vs. 200–500 in unvaccinated children), low-grade fever and faster recovery. Two doses reduce the risk of severe chickenpox by 98%.

How do I relieve chickenpox itching?

Lukewarm (not hot) oatmeal baths, calamine lotion on lesions, and oral antihistamines as directed by your doctor help relieve itching. Keep nails short and clean to prevent scratching and secondary bacterial infection.

Is chickenpox dangerous for babies under 1 year?

Babies under 1 year are at higher risk of complications because they cannot yet be vaccinated. If a baby in this age group is exposed to chickenpox, see a pediatrician immediately — varicella-zoster immunoglobulin (VZIG) may be indicated as prophylaxis.

Chickenpox in Children: Symptoms, Treatment & Vaccine

Your child woke up covered in itchy red spots — chickenpox (varicella) is one of the most recognizable childhood infections. Although it is usually mild, knowing exactly what to do at each stage, which medications to avoid (ibuprofen and aspirin are contraindicated), and when to head to the doctor can make a real difference. This guide covers everything expat and local families in São Paulo need to know.

How Chickenpox Progresses — Day by Day

Understanding the typical timeline helps parents know what to expect and when to act.

Days 1–2 (Prodrome)

• Low-grade fever (37.5–38.5 °C)
• Fatigue and loss of appetite
• Mild headache
• No rash yet — but already contagious

Days 2–4 (Rash onset)

• Small red spots appear on face, scalp, trunk
• Spots quickly become fluid-filled blisters
• Intense itching begins
• New crops of blisters appear in waves

Days 4–7 (Peak)

• 200–500 blisters in typical cases
• Blisters spread to limbs
• Lesions in mouth, throat, genitals possible
• Fever may peak (up to 39 °C)

Days 7–10 (Resolution)

• Blisters start drying and crusting
• No new blisters = recovery underway
• No longer contagious once fully crusted
• Scabs fall off without leaving scars (if not scratched)

Recognizing Chickenpox: Key Symptoms

The rash is the hallmark — but it is not the only sign. Here is what to look for:

Polymorphic rash

Spots, blisters, and crusts all present at the same time — this mix is diagnostic

Centripetal distribution

More lesions on the trunk, fewer on arms and legs

Scalp involvement

Blisters on the scalp are characteristic of chickenpox

Intense itching

Often described as the most distressing symptom — scratching risks secondary infection

Mucosal lesions

Painful sores in the mouth or throat may interfere with eating and drinking

Fever pattern

Fever rises and falls with each new crop of blisters — this is normal

CRITICAL: Ibuprofen and Aspirin are CONTRAINDICATED

Never give ibuprofen (Advil, Motrin) or aspirin to a child with chickenpox:

Ibuprofen dramatically increases the risk of necrotizing fasciitis (flesh-eating bacterial infection) — a life-threatening complication
Aspirin can cause Reye syndrome — a rare but severe liver and brain condition

✓ Use paracetamol (acetaminophen / Tylenol) only — safe and effective for fever and discomfort.

Treatment and Home Care

Chickenpox in healthy children is generally managed at home. The goal is to relieve symptoms and prevent complications from scratching.

Paracetamol for fever/pain

Dose: 10–15 mg/kg every 4–6 hours as needed. Never exceed 5 doses in 24 hours.

Antihistamines for itching

Oral antihistamines (e.g., hydroxyzine) help reduce itching, especially at night. Ask your pediatrician for the right dose.

Calamine lotion

Applied directly to lesions to soothe itching. Safe and widely available without prescription.

Cool baths

Lukewarm baths with colloidal oatmeal can provide significant itch relief. Pat dry gently — do not rub.

Cut fingernails short

Prevents skin breaks from scratching that allow bacteria in. Use mittens for very young children.

Keep skin clean and dry

Gentle soap and water on lesions daily. Light, breathable clothing reduces irritation.

Hydration

Encourage fluids. If mouth sores make drinking painful, try cold liquids and soft foods.

Antivirals (selected cases)

Acyclovir may be prescribed for adolescents, immunocompromised children, or severe cases — not routine for healthy young children.

Questions about your child's chickenpox?

Dr. Paula Andrade sees expat families in English. Book a virtual or in-person consultation.

Book a Consultation

When to See a Doctor — Warning Signs

Most cases resolve at home, but these signs require prompt medical evaluation:

Go to the ER or call your pediatrician immediately if:

Fever above 39.5 °C persisting beyond day 4, or new fever after improvement
Skin around blisters becomes hot, red, very swollen, or oozes pus (superinfection)
Child is unusually lethargic, difficult to wake, or confused
Breathing difficulty or rapid breathing
Severe headache, neck stiffness, or sensitivity to light (meningitis signs)
Refusal to drink fluids for more than 6 hours (dehydration risk)
Blisters on eyelids or conjunctiva
Extreme pain disproportionate to the rash — rule out necrotizing fasciitis

Isolation and School Return

Isolation Rules

Contagious from: 1–2 days before the rash appears until all lesions are completely crusted and dried (not just mostly)
Typical isolation period: 7–10 days from rash onset
School/daycare return: Only when ALL blisters are dried and crusted — Brazilian schools and the SBP (Brazilian Pediatrics Society) are strict on this
Avoid contact with: Newborns, pregnant women (who have not had chickenpox or the vaccine), and immunocompromised individuals — chickenpox can be very serious for them

Chickenpox Vaccine in Brazil

The varicella vaccine is the best protection against chickenpox — and it is available free through Brazil’s public health system (SUS).

Schedule	Doses	Notes
SUS (public)	1 dose at 15 months	Combined MMRV vaccine (measles, mumps, rubella, varicella)
SBP (pediatric society)	2 doses: 12 months + 15 months	Two doses provide better protection (~98% vs ~85% with one dose)
Catch-up (unvaccinated)	2 doses, ≥3 months apart	Recommended up to age 12 for unvaccinated children with no history of disease
Post-exposure	1 dose within 72–120 hours of contact	Can prevent or significantly attenuate disease if given quickly

Possible Complications

Complications are uncommon in healthy children but can be serious. Higher risk groups include newborns, adolescents, adults, and the immunocompromised.

Bacterial superinfection

Most common complication. Scratching breaks skin and allows Staphylococcus or Streptococcus in. Can progress to cellulitis or, rarely, necrotizing fasciitis.

Pneumonia

More common in adolescents and adults. Presents with cough and breathing difficulty during active chickenpox.

Neurological complications

Cerebellar ataxia (unsteady walking) is rare but well-recognized. Encephalitis is even rarer but serious.

Shingles (herpes zoster)

VZV remains latent in nerve ganglia after infection. Can reactivate as shingles years later — more common in immunocompromised individuals.