Chickenpox (varicella) is a highly contagious viral infection that causes an itchy rash of spots which turn into fluid-filled blisters and then crust over. It is usually mild in children and gets better in 1 to 2 weeks, but it can be serious in newborns, pregnant women, adults and people with weak immune systems. A person is infectious from about 2 days before the rash appears until all the blisters have crusted over.
Key facts
- Cause: varicella-zoster virus
- Spread: through the air (coughs and sneezes) and by touching fluid from the blisters
- Incubation period: usually 10 to 21 days after exposure
- Infectious period: about 2 days before the rash until all spots have crusted (often around 5 days after the rash starts)
- Later life: the virus stays in nerves and can reactivate as shingles
Symptoms and stages of the rash
- Before the rash: fever, tiredness, aches, loss of appetite
- Spots: small red spots, often starting on the chest, back, face or scalp, then spreading
- Blisters: spots fill with fluid and are very itchy
- Crusts: blisters burst and scab over
New spots keep appearing for several days, so you see spots, blisters and scabs at the same time. On brown and black skin, spots may look darker, purple or grey rather than red.
Home care
- Give plenty of fluids
- Paracetamol for fever and pain if needed
- Do not give ibuprofen unless a doctor advises, because it is linked to serious skin infections in chickenpox
- Never give aspirin to children (risk of Reye’s syndrome)
- Cool baths, loose cotton clothes, calamine or cooling gels to soothe itching
- Keep nails short and consider cotton mittens for babies to prevent scratching
- Keep the child away from school or nursery until all spots have crusted
Who is at higher risk?
- Newborn babies
- Pregnant women who have never had chickenpox
- Adults and teenagers
- People with weakened immunity (cancer treatment, high-dose steroids, uncontrolled HIV)
If any of these people are exposed, they should contact a doctor quickly. Preventive treatment may be offered.
Warning signs: get urgent help
- Skin around blisters becomes red, hot, swollen and painful (bacterial infection)
- Difficulty breathing or chest pain (possible pneumonia)
- Drowsiness, confusion, severe headache, stiff neck, or unsteady walking
- A child who is very unwell, dehydrated or not improving
- Bleeding into the spots
Infection control in hospital
- Airborne and contact precautions: single room, ideally negative pressure; door closed
- Only staff with immunity to chickenpox should care for the patient
- Non-immune staff exposed to chickenpox should report to occupational health; they may need to stay off work during the incubation period
- Check the immunity of pregnant staff and visitors
- Continue isolation until all lesions have crusted
Vaccination
A varicella vaccine is available and is part of routine childhood schedules in many countries, including the US and Canada. Health workers without immunity are often offered the vaccine. Check your national schedule.
Frequently asked questions
Can you get chickenpox twice?
It is uncommon. Most people are immune after one infection, but the virus can reactivate later as shingles.
When can a child go back to school after chickenpox?
Once all the spots have crusted over, usually about 5 days after the rash starts.
Can adults catch chickenpox from shingles?
People who have never had chickenpox can catch chickenpox (not shingles) from fluid in shingles blisters.
Related reading: Standard and transmission-based precautions · Measles nursing care · Temperature measurement and fever
Checked against NHS guidance on chickenpox. Updated 5 November 2026.