Overview
Chickenpox, or varicella, is a highly contagious illness caused by the varicella-zoster virus, producing an itchy, blister-like rash along with fever and tiredness, most often affecting children before routine vaccination.
Disease Summary
- Category
- Infectious Disease
- Cause
- Varicella-zoster virus (VZV)
- Transmission
- Spreads through close contact with an infected person, including airborne respiratory droplets and contact with fluid from blisters
- Body System
- Skin
- Preventable
- Yes
- Curable
- Yes
Symptoms
Common Symptoms
Chickenpox illness usually lasts about 4 to 7 days.
Itchy Rash
Small red spots that develop into fluid-filled blisters, usually starting on the chest, back, or face before spreading.
Fever
Mild to moderate fever often accompanies or precedes the rash.
Tiredness
Fatigue and low energy are common in the days before and during the rash.
Loss of Appetite
Reduced appetite is common, especially in the first few days of illness.
Danger Signs
Seek medical attention promptly if any of the following develop.
High Fever
A very high or persistent fever may indicate a secondary infection and needs evaluation.
Signs of Skin Infection
Redness, warmth, or pus around blisters can indicate a bacterial skin infection.
Difficulty Breathing
May indicate pneumonia, a serious complication, especially in adults.
Confusion or Difficulty Waking
Can indicate a rare but serious complication affecting the brain and requires emergency care.
Diagnosis
Clinical Assessment
Diagnosis is usually made by recognizing the characteristic itchy, blister-like rash and reviewing exposure history.
Rash Pattern Review
The presence of spots, blisters, and scabs at the same time is a hallmark feature of chickenpox.
Laboratory Testing
In uncertain cases, testing of fluid from a blister can confirm varicella-zoster virus infection.
Laboratory Tests
Polymerase Chain Reaction (PCR)
The preferred test to confirm varicella-zoster virus infection when diagnosis is uncertain.
Direct Fluorescent Antibody (DFA) Test
Detects viral antigens directly from a skin lesion sample.
Varicella Antibody Test
Can help confirm past infection or immunity, including in people being assessed for vaccination.
Treatment
Supportive Care
Calamine lotion, oatmeal baths, and keeping fingernails trimmed can relieve itching and reduce the risk of skin infection.
Antiviral Medication
Recommended for people at higher risk of severe illness, such as older adults, pregnant women, and those with weakened immune systems.
Prevention
Get the chickenpox vaccine
Two doses of varicella vaccine provide strong protection and are recommended for children, adolescents, and adults without evidence of immunity.
Avoid close contact with infected individuals
Chickenpox spreads easily through close contact, so limiting exposure to infected people reduces the risk of transmission.
Wash hands regularly
Good hand hygiene helps reduce the spread of the virus, especially in households and childcare settings.
Stay home while contagious
Staying away from school, work, or public places until all blisters have crusted over prevents spreading the virus to others.
Risk Factors
High Risk
These factors substantially increase the likelihood of getting chickenpox.
- No prior chickenpox infection or vaccination
- Close household contact with an infected person
- Weakened immune system
Increased Risk
These groups face a higher risk of severe chickenpox.
- Infants and young children in group childcare settings
- Pregnant women without immunity
- Adults, who tend to have more severe disease than children
Additional Contributing Factors
Other factors linked with an increased likelihood of severe illness.
- Chronic skin or lung conditions
- Long-term steroid or immunosuppressive medication use
- Living or working in crowded settings
Complications
Bacterial Skin Infection
Scratching blisters can introduce bacteria, leading to skin infections that may need antibiotics.
Pneumonia
A potentially serious complication that occurs more often in adults than in children.
Shingles (Later in Life)
The virus remains dormant in the body and can reactivate years later as shingles, a painful nerve and skin condition.
When to Seek Medical Care
High or Persistent Fever
May indicate a secondary infection and should be evaluated by a healthcare provider.
Signs of Skin Infection
Redness, warmth, or pus around blisters needs medical assessment.
Difficulty Breathing
May indicate pneumonia and requires prompt medical attention.
Confusion or Severe Headache
Can indicate a rare but serious complication affecting the brain and needs emergency care.
Prognosis
Generally Mild in Healthy Children
Most healthy children recover fully within 4 to 7 days without lasting effects.
More Severe in Adults
Adults tend to experience more severe symptoms and a higher risk of complications than children.
Lifelong Immunity After Infection
Having chickenpox once usually provides lifelong immunity, though the virus can still reactivate later as shingles.
Differential Diagnosis
Hand, Foot, and Mouth Disease
Causes a blister-like rash but typically affects the hands, feet, and mouth rather than spreading across the whole body.
Impetigo
A bacterial skin infection that can cause blisters but lacks the widespread distribution typical of chickenpox.
Shingles (Herpes Zoster)
Caused by the same virus but typically appears as a localized band of blisters rather than a widespread rash.
Measles
Causes fever and rash but typically presents with flat, red spots rather than fluid-filled blisters.
References
Centers for Disease Control and Prevention (CDC)
CDC guidance on chickenpox symptoms, spread, and prevention.
Centers for Disease Control and Prevention (CDC), Treatment
CDC guidance on treating chickenpox symptoms and preventing complications.
Centers for Disease Control and Prevention (CDC), Vaccine Recommendations
CDC recommendations on the varicella vaccine.
Frequently Asked Questions
Is chickenpox contagious?
Yes. Chickenpox is highly contagious and spreads easily through close contact with an infected person.
Can you get chickenpox more than once?
It’s uncommon, but possible; most people who have had chickenpox develop lifelong immunity.
Is the chickenpox vaccine effective?
Yes. Two doses provide strong protection, and vaccinated people who still get chickenpox usually have much milder illness.
Can chickenpox lead to shingles?
Yes. The virus stays dormant in the body after chickenpox and can reactivate later in life as shingles.