Is Chickenpox Contagious?

What is chickenpox?

Chickenpox is a contagious viral infection that causes an itchy red rash that eventually blisters.
Chickenpox is a contagious viral infection that causes an itchy red rash that eventually blisters.

Chickenpox is a disease is caused by a virus (varicella zoster virus, varicella, or VZV) that results in a blister-like rash with intense itching, tiredness, and fever. In normal individuals without immune system problems, chickenpox usually will last about five to 10 days and then resolve. Before vaccination was available, about 4 million people (mainly children) were infected each year. Once infected, the virus can remain dormant in nerve cells and after many years (in adults about 50 years old or older) the virus can be reactivated to cause the condition known as zoster (shingles).

Is chickenpox contagious?

Chickenpox is highly contagious and easily passed from person to person by direct contact (saliva, kissing) and indirect contact with blister fluid that touches objects like toys or utensils. In addition, chickenpox can be transmitted by contaminated droplets produced during coughing and sneezing. For those individuals who develop zoster (shingles), the fluid formed in blisters that arise during the disease is also contagious for chickenpox.

Chickenpox is not contagious from humans to dogs or other pets; chickenpox is a disease mainly confined to humans.

How will someone know that he or she has chickenpox?

Although chickenpox is usually thought of as a childhood disease, anyone who has not been vaccinated or infected can get the disease. Even about 25%-30% of those vaccinated may still get a mild form of the disease if exposed. About one to two days before characteristic blisters develop, individuals usually have a high fever, headache, loss of appetite, and are somewhat lethargic. The rash that develops quickly produces fluid-filled blisters that usually appear first on the chest and face and then spread to the rest of the body. This is when chickenpox is usually clinically diagnosed; lab tests are seldom used to diagnose the disease. Blisters usually last about one week before all of them form scabs.

How is chickenpox transmitted?

Chickenpox is spread easily through the air in contaminated droplets produced by coughing and sneezing. Contact with secretions (mucus, blister fluid, for example) either directly by touching secretions or indirectly (if the secretions contaminate toys, utensils, and other objects) can result in spread of chickenpox. In addition, blister fluid produced in individuals who have shingles also can spread varicella virus, the cause of chickenpox, to anyone who is susceptible (unvaccinated individuals).

How will someone know when he or she is cured of chickenpox?

Once a person acquires the chickenpox infection, there is no cure because in most people, the virus remains in a dormant form within the nerve cells. These dormant viruses are responsible for the disease shingles (zoster).

However, the closest thing to a cure is the chickenpox vaccine that can render the vaccinated person immune to this virus for many years. If the immune system in an individual weakens, it is possible for the individual who was vaccinated in childhood to develop shingles, but even shingles may be prevented by giving older adults a vaccine specifically designed to prevent shingles.

A variation of the answer to knowing when someone is "cured" of chickenpox would be to ask when a person with chickenpox or shingles is no longer contagious. Individuals are contagious during the incubation period (one to two days before symptoms and signs develop) and then for about an additional seven to 10 days (when all of the blisters have crusted over). For shingles, the disease becomes contagious when the blisters begin to form and becomes noncontagious after all the blisters have developed crusts.

When should someone contact a medical provider about chickenpox?

Most children with chickenpox do well and recover on their own without specific treatment. However, a medical caregiver may need to be contacted if the symptoms are severe or if someone is at high risk for complications. For example, pregnant women, others who have weakened immune systems, and very young infants are at risk for complications. Complications of chickenpox may include the following:

Individuals with shingles may need to contact medical caregivers for treatment and pain control; if shingles appears on the face especially near the eye, a medical caregiver and/or ophthalmologist should be contacted immediately.


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United States. Centers for Disease Control and Prevention. "Chickenpox (Varicella)." Dec. 31, 2018. <>.