Chickenpox

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
Founder, WikiMD Wellnesspedia &
W8MD's weight loss doctor NYC
Philadelphia GLP-1 weight loss and GLP-1 clinic NYC

Chickenpox
Varicela Aranzales.jpg
A patient presenting with the characteristic blisters of chickenpox
Synonyms	Varicella
Specialty	Infectious disease, Dermatology, Pediatrics
Symptoms	Small, itchy blisters, rash, fever, headache, fatigue, loss of appetite
Complications	Skin infection, pneumonia, encephalitis, Reye's syndrome, scarring, shingles
Usual onset	10–21 days after exposure
Duration	5–10 days
Types	Primary varicella (chickenpox), Secondary reactivation (shingles)
Causes	Varicella zoster virus
Risk factors	Immunodeficiency, pregnancy, infancy, adult age, lack of vaccination
Diagnosis	Clinical diagnosis, polymerase chain reaction (PCR), serology
Differential diagnosis	Smallpox, measles, insect bites, impetigo, herpes simplex
Prevention	Varicella vaccine, herd immunity
Treatment	Supportive care, symptom management, antiviral therapy in severe cases
Medication	Paracetamol (acetaminophen), calamine lotion, acyclovir, antihistamines
Prognosis	Excellent in healthy children; risk of complications in adults and immunocompromised
Frequency	Common in unvaccinated populations; incidence reduced in countries with routine vaccination
Deaths	~6,400 per year globally (including from shingles)

A single blister, typical during the early stages of the rash

Chickenpox

Chickenpox (also known as varicella) is a highly contagious viral infection caused by the varicella-zoster virus (VZV). It is characterized by an itchy skin rash, blisters, and fever. The infection is typically mild in children but can be more severe in adults and people with weakened immune systems. Chickenpox is preventable through vaccination.

Symptoms

Chickenpox generally begins with flu-like symptoms, such as:

• Fever
• Headache
• Fatigue
• Loss of appetite
• Sore throat
• Swollen lymph nodes

These are followed by a distinctive rash, which:

• Starts as small, red, itchy spots
• Progresses to fluid-filled blisters
• Scabs over within a few days

The rash often starts on the face, chest, and back, spreading across the body.

Causes

Chickenpox is caused by the varicella-zoster virus, a member of the herpesvirus family. It spreads via:

• Direct contact with blister fluid
• Airborne droplets from coughs or sneezes
• Contact with contaminated surfaces

Diagnosis

Diagnosis is usually based on clinical symptoms, especially the characteristic rash. In uncertain cases, laboratory tests such as:

• Blood tests
• PCR tests
• Swabs of skin lesions

Treatment

Treatment focuses on symptom relief. Most cases resolve without complications. Common approaches include:

Medications

• Antiviral drugs (e.g., acyclovir) for high-risk individuals
• Antihistamines to reduce itching
• Acetaminophen or ibuprofen to reduce fever (aspirin should be avoided due to risk of Reye's syndrome)

Home care

• Cool baths or wet compresses
• Calamine lotion
• Short, clean fingernails to prevent scratching
• Loose-fitting clothing

Prevention

Prevention is mainly through vaccination:

• Two doses of the chickenpox vaccine (varicella vaccine)
• First dose: 12–15 months
• Second dose: 4–6 years

Other preventive measures:

• Good hand hygiene
• Avoiding contact with infected individuals

Complications

While typically mild, chickenpox can cause serious complications, especially in:

• Pregnant women
• Newborns
• Immunocompromised individuals

Potential complications include:

• Bacterial skin infections
• Pneumonia
• Encephalitis
• Dehydration
• Sepsis
• Reye's syndrome (linked to aspirin use)

Shingles and Immunity

After recovery, the virus becomes dormant in nerve cells. It may reactivate later in life as shingles (herpes zoster), causing a painful rash. Individuals typically gain lifelong immunity to chickenpox after infection.

Post-exposure Prophylaxis

For exposed individuals at high risk, options include:

• Varicella vaccine (within 3–5 days of exposure)
• Varicella-zoster immune globulin (VZIG) for immunocompromised patients

Public Health and Global Impact

Chickenpox remains common in countries without widespread vaccination programs. In high-income countries, routine immunization has dramatically reduced incidence and complications.

School and Travel Considerations

Many schools require documentation of chickenpox immunity. During outbreaks, unvaccinated students may be excluded temporarily. Travelers should confirm their immunity status before visiting high-risk areas.

See also

• Varicella zoster virus
• Herpesvirus
• Shingles
• Childhood infectious diseases
• Vaccination