What is Chickenpox?

Chickenpox is a highly contagious disease caused by the varicella zoster virus (VZV); 90% of all people will catch the disease before age ten. Infection is spread by nasal discharge of the virus or by contact with a chickenpox blister, which is the hallmark of the disease. The most contagious period is from two days before the onset of the rash to four days after the rash has appeared.

Chickenpox is a self-limiting infection that normally resolves in ten to fourteen days. After an attack of chickenpox, most individuals gain lifelong immunity to reinfection. Infection is usually experienced in childhood, but can afflict adults who have never been exposed to the virus or who have a weakened immune system.

How is it diagnosed?

Chickenpox signs and symptoms

The following are usually mild in children, severe in adults:

  • Fever.
  • Abdominal pain or a general ill feeling that lasts 1-2 days.
  • Skin eruptions that appear almost anywhere on the body, including the scalp, penis, and inside the mouth, nose, throat or vagina. They may be scattered over large areas, and they occur least on the arms and legs. Blisters collapse within 24 hours and form scabs. New crops of blisters erupt every 3 to 4 days.
  • Adults have additional symptoms that resemble influenza.

History is of exposure to another infected person (but exposure may have already occurred before the other's disease became apparent). Chickenpox is characterized by an itchy blister-like rash, usually beginning on the face and trunk, and spreading to the extremities and mucous membranes. Adults often report a fever, abdominal pain and general discomfort (malaise). These symptoms lessen as the blisters heal.

Physical exam will show blisters on the face and trunk, which may have spread to the scalp, inside the mouth, ears, nose, and penis or vagina. Chickenpox blisters range in size from five to ten millimeters in diameter, have a reddened base, and appear in clusters over a two- to four-day period. Some people have only a few blisters while others may have several hundred. The blisters break and crust over in one or two weeks (it may take longer in immunocompromised individuals, especially with AIDS).

Tests: Usually the history and physical exam will be sufficient to make the diagnosis. Blood tests for VZV-specific antibodies or recovery of virus from early lesions may confirm chickenpox infection.

How is Chickenpox treated?

Itching can be treated with over-the-counter drying lotions and antihistamines. To reduce fever, nonsteroidal anti-inflammatory drugs should be used. Aspirin should be avoided. When blisters appear, individuals should be quarantined for seven days to reduce the spread of the infection to other individuals.

Prevention is the best treatment for chickenpox. An effective vaccine is available for healthy children and adults at risk. The vaccine helps people develop their own antibodies (immune protection) against chickenpox, but in some cases it is necessary to give ready-made immune protection in the form of varicella-zoster immune globulin (VZIg). VZIg protects those whose immune systems are too weak to fight the disease. VZIg is given to newborns whose mothers had chickenpox at the time of delivery, individuals with lymphoma or leukemia, individuals with AIDS or other diseases that cause depressed immunity, and individuals receiving immune-suppressing drugs). VZIg has been approved for preventative treatment if a person has been exposed to chickenpox.

Individuals who exhibit severe complications from chickenpox or suffer from other diseases that impair their immunity may be treated with antiviral medicine. Current anti-VZV drugs are members of a class of compounds called nucleoside analogs. These compounds inhibit the formation of new virus particles, reduce the spread of the virus and minimize the formation of new lesions. To be effective, this treatment must begin within 72 hours after the appearance of the rash.

Antibiotics are used if bacterial infections develop in the lesions.


  • The following non-prescription medicines may decrease itching:
    • Topical anesthetics and topical antihistamines, which provide quick, short-term relief. Preparations containing lidocaine and pramoxine are least likely to cause allergic skin reactions. Lotions that contain phenol, menthol and camphor (such as calamine lotion) may be recommended. Follow package instructions.
  • If you must reduce fever, use acetaminophen. Never use aspirin as it may contribute to the development of Reye's syndrome (a form of encephalitis) when given to children during a viral illness.
  • Acyclovir (brand name Zovirax), an antiviral medication, may be prescribed.
Information Brand Generic Label Rating
Zovirax Zovirax Acyclovir Off-Label

Prograf (Tacrolimus), Famvir (Famciclovir), Valtrex (Valacyclovir)

What might complicate it?

The most common complication is bacterial infection of the blisters. This condition results from not washing the skin or picking at the lesions with dirty fingers. Permanent scarring at the blister site occasionally occurs. After chickenpox has cleared, portions of the original infecting virus remain in the body in a dormant state; it can become reactivated later in life to cause shingles in some people. Uncommonly, chickenpox can infect the lungs, heart, liver, brain, ears, or eyes.

Predicted outcome

The predicted outcome for uncomplicated chickenpox is excellent. Untreated complications of chickenpox can lead to prolonged disability and/or death. Mortality rate in adults is three per 10,000 cases.


The skin rash can appear similar to smallpox, generalized herpes simplex infection, and impetigo. Individuals who develop serious zoster infection as a result of the chickenpox will require extended terms of disability. The extent of these disabilities must be considered on an individual basis.

Appropriate specialists

Internist, dermatologist, ophthalmologist, obstetrician, respiratory disease specialist, neurologist and infectious disease specialist.

Notify your physician if

  • You or your child has symptoms of chickenpox.
  • Lethargy, headache or sensitivity to bright light develop.
  • Fever rises over 101°F (38.3° C).
  • Chickenpox lesions contain pus or otherwise appear infected.
  • A cough occurs during a chickenpox infection.

Last updated 22 December 2015


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