Chickenpox: the itchy blister rash, day by day
Last updated September 3, 2026.
Chickenpox is the classic childhood rash: crops of intensely itchy blisters that come in waves over about a week. Caused by the varicella-zoster virus, it is wildly contagious, and most children ride it out at home with nothing more than itch relief and time. It is much rougher on adults, newborns, pregnant women, and anyone with a weakened immune system, which is where the real management happens.
What does it look like, day by day?
After an incubation of 10-21 days, it starts with 1-2 days of fever, tiredness, and loss of appetite, then the rash: red spots that turn within hours into fluid-filled blisters on red bases, classically described as dewdrops on rose petals. New crops keep appearing for 3-5 days, so spots, blisters, and scabs coexist, most densely on the trunk, face, and scalp, and sometimes inside the mouth, eyelids, and genitals. Blisters scab over about 5 days after appearing. A child is contagious from 2 days before the rash until every blister has scabbed, usually 5-7 days after it starts. Watch the skin for the one common complication: bacterial infection of scratched blisters, showing as increasing redness, warmth, swelling, or oozing.
Who needs more than home care?
Healthy children under 12: home care, no antivirals needed. The groups that need medical assessment, usually for the antiviral acyclovir (most effective if started within 24 hours of the rash): anyone 13 or older, pregnant women, newborns, people with weakened immunity or on steroids, and children with eczema, lung, or heart conditions. Pregnancy matters twice over: chickenpox can cause pneumonia in the mother, and infection around delivery can be dangerous for the newborn, so a pregnant woman without a history of chickenpox who is exposed should contact her midwife or doctor urgently, ideally within 10 days of exposure, for protective antibody treatment.
What actually helps?
- Acetaminophen for fever: never ibuprofen in chickenpox (linked to severe skin infections) and never aspirin under 16 (Reye's syndrome risk).
- Calamine lotion and moisturizers: calamine or a cooling emollient gel eases the itch. Antihistamines like cetirizine help at night.
- Baths: cool or lukewarm baths, some families add oatmeal; pat dry, do not rub.
- Stop the scratching: keep nails short and clean, use mittens or socks on hands for babies and toddlers, and dress in loose cotton. Scratching is what scars and infects.
- Fluids and rest: cold drinks and ice pops if the mouth is affected; normal school exclusion until fully scabbed.
When is it an emergency?
Urgent care for: breathing difficulty or persistent cough (varicella pneumonia, the adult killer), severe headache with a stiff neck, confusion, or unsteadiness, a high fever returning after the first few days, blisters that become red, hot, swollen, or pus-filled, any eye involvement, or refusal to drink with signs of dehydration. Emergency services for breathing difficulty, confusion, or seizures. A newborn with chickenpox, or a pregnant woman who develops the rash, needs same-day specialist contact. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
How long is chickenpox contagious?
From 1-2 days before the rash appears until every blister has scabbed over, which usually takes 5-7 days from the first spots. The before-the-rash window is why it spreads so efficiently through classrooms and families. Children can return to school or nursery once all blisters have scabbed and they feel well. Note the different rule for flights and vulnerable contacts: airlines and some settings may have their own requirements.
Can you get chickenpox twice?
Rarely, but it happens. One infection usually gives lifelong immunity, but second cases are documented, typically milder. More relevant is the other second act: the virus never leaves the body, and decades later it can reactivate as shingles, a painful stripe of blisters on one side. The chickenpox vaccine prevents the original infection, and the shingles vaccine (offered to older adults in many countries) addresses the reactivation.
Is chickenpox dangerous for adults?
Significantly more than for children. Adults have higher rates of varicella pneumonia, the complication that sends chickenpox to hospital, with smokers and pregnant women at the top of that risk list. Adults with suspected chickenpox should contact a clinician promptly, because the antiviral acyclovir is routinely offered to anyone 13 or older and works best started within 24 hours of the rash. Smoking adults with chickenpox and a new cough need urgent assessment.
Why is ibuprofen not allowed in chickenpox?
Studies have linked ibuprofen and other NSAIDs used during chickenpox with a higher rate of severe secondary skin infections, including necrotizing soft tissue infections. The association is strong enough that guidance says avoid them during the illness. Acetaminophen (paracetamol) is the recommended fever and pain reliever. Aspirin is separately banned under 16 because of Reye's syndrome, a rare but dangerous reaction to aspirin during viral illnesses.
Do chickenpox scars go away?
Most marks fade over months, but scars from scratched or infected blisters can be permanent, which is the practical argument for itch control and nail trimming. The round, pale, slightly indented scars are the typical pattern. Fresh red marks left after scabs fall off are not scars yet; they fade over 6-12 months. Sun protection on healing skin helps, since UV darkens fresh marks.
What should I do if I am pregnant and exposed to chickenpox?
Contact your midwife, doctor, or maternity unit promptly, within days of the exposure. The first step is a blood test: most adults are immune from childhood infection, even without remembering it. If you are not immune, you can be offered varicella-zoster immune globulin, ideally within 10 days of exposure, to blunt or prevent infection. Chickenpox in pregnancy carries risks to you (pneumonia) and, at certain stages, to the baby, so exposure is a same-week phone call, not a wait-and-see.
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