- Also called:
- varicella
- Key People:
- Maurice Hilleman
- On the Web:
- National Center for Biotechnology Information - Overview: Chickenpox (Nov. 01, 2026)
chickenpox
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What is chickenpox?
Chickenpox is a highly contagious viral illness characterized by a rash of itchy, fluid-filled blisters on the skin. It is caused by the varicella-zoster virus (VZV), the same virus responsible for shingles.
Symptoms typically appear about two weeks after infection and include a slight fever followed by the eruption of red papules that develop into vesicles. These blisters eventually scab over and usually heal without scarring. While chickenpox is generally mild, especially in children, it can be severe or fatal for individuals with weakened immune systems. Vaccination is available and highly effective in preventing the disease.
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What causes chickenpox?
Chickenpox is caused by the varicella-zoster virus (VZV). This highly contagious viral disease typically occurs in epidemics and most often affects children between the ages of two and six, though it can impact individuals of any age. VZV is the same virus responsible for herpes zoster, commonly known as shingles. Chickenpox represents the body's reaction to an initial encounter with the VZV. Fortunately, a vaccine is available to prevent infection.
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What are the main symptoms of chickenpox?
Chickenpox, a contagious viral illness caused by the varicella-zoster virus (VZV), typically begins with a slight fever for about 24 hours before the eruption of symptoms. The primary symptom is a rash that starts as raised, itchy red papules, usually on the back or chest. Within 12 to 24 hours, these develop into small, fluid-filled blisters that become cloudy and eventually form scabs. New spots continue to appear for the first three days, meaning all stages of the rash can be present simultaneously. The eruption is most prominent on covered areas of the body but can also appear on the face, limbs, and the mucous membranes of the mouth.
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How does chickenpox spread from one person to another?
Chickenpox is a highly contagious viral disease caused by the varicella-zoster virus (VZV). It spreads through direct contact with the rash, blisters, or through respiratory droplets from an infected person's cough or sneeze. The virus can also spread by touching surfaces or objects that have been contaminated with the virus.
It is important to note that while a person with herpes zoster (shingles) can transmit VZV to someone who hasn't had chickenpox or the vaccine, causing them to develop chickenpox, the reverse is not true. Chickenpox is preventable with vaccination.
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What are some possible complications of chickenpox?
While chickenpox is typically a mild illness, complications can occur, though they are uncommon. These can include secondary bacterial infections of the skin, which may spread to other organ systems in the body.
It is important to note that individuals with compromised immune systems are at a higher risk for severe or even fatal outcomes from chickenpox.
The varicella-zoster virus (VZV) that causes chickenpox can also lead to herpes zoster (shingles) later in life.
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How can people prevent or treat chickenpox?
Chickenpox is a contagious viral illness caused by the varicella-zoster virus (VZV), characterized by a rash of itchy blisters. While the illness typically requires no specific treatment beyond isolation to prevent spread and medications to alleviate itching, prevention is highly effective through vaccination.
The varicella vaccine, available since 1995 in the United States, provides lifelong protection for most individuals after receiving the recommended two doses. For those at high risk who have been exposed, zoster immune globulin (ZIG) can be administered to help prevent the development of chickenpox, though its protection is temporary.
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chickenpox, contagious viral disease characterized by an eruption of vesicles (small blisters) on the skin. The disease usually occurs in epidemics, and the infected persons are generally between two and six years old, although they can be of any age. Chickenpox is caused by the varicella-zoster virus (VZV), the same virus that causes herpes zoster (also called zoster, shingles, or zona), a localized eruption of large blisters. Chickenpox is the clinical reaction to a first exposure to the virus. Infection is preventable with vaccination (see List of Vaccine-Preventable Diseases).
Symptoms
The incubation period is about two weeks following infection with VZV. There are practically no premonitory symptoms, though slight fever for about 24 hours may precede the eruption. A number of raised itchy red papules appear on the back or chest; within 12 to 24 hours these develop into tense vesicles filled with a clear fluid, which in another 36 hours or so becomes opalescent. During the fourth day the vesicles shrivel up and become scabs. Eventually the scabs fall off, usually leaving no scar.
Fresh spots continue to appear during the first three days, so that at the end of that time they can be seen in all stages of growth and resolution. The eruption is most marked on areas covered by clothing, but it also occurs on the face and limbs and on the mucous membrane of the mouth and palate. The temperature of the infected person rarely rises above 39 °C (102 °F). The disease runs a favourable course in most cases and usually produces permanent immunity.
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Treatment
The illness requires no treatment; the patient should be isolated at home to prevent infection of others. It is particularly important that the patient avoid contact with persons who have suppressed immune systems, in whom chickenpox can be severe or fatal. The patient also should be prevented from scratching, which could lead to ulceration of the vesicles and scarring; common antipruritic skin medications such as calamine lotion may be helpful. Complications, although uncommon, include secondary invasion of the skin by bacteria and spread of those bacteria to virtually any organ system in the body.
Herpes zoster
After recovery, VZV may settle in a nerve ganglion and be reactivated many years later. The cause of reactivation is not known. Upon reactivation, the virus travels along a nerve to the skin and causes herpes zoster. In most cases the lesions of herpes zoster occur in the distribution of a dermatome, an area of skin associated with the branch of a single spinal nerve. For this reason, herpes zoster is usually unilateral (on one side of the body).
Severe pain is felt in the area of the blisters, which last from three to five days and then subside on their own. A person with herpes zoster is able to infect another person with VZV, resulting in chickenpox, but the reverse does not occur, because herpes zoster is a result of reactivation of latent virus from a prior varicella infection. Specific antiviral agents may have a role in the treatment of herpes zoster.
Prevention
In 1995 a chickenpox vaccine prepared from a live, attenuated strain of VZV was approved for use in the United States. The vaccine provides lifelong protection against the disease for most children, adolescents, and adults who receive the recommended two doses.
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In cases when high-risk individuals, such as pregnant women and persons with compromised immune systems, have been exposed to VZV, injections of zoster immune globulin (ZIG) may be administered. ZIG is prepared from the plasma of adults who have recently experienced herpes zoster and therefore contains antibodies against VZV that can help prevent the development of chickenpox in exposed individuals. The protection it provides, however, is only temporary.