Chickenpox

Definition

Chickenpox is a viral infection in which a person develops very itchy blisters all over the body. It was more common in the past. The illness is rare today because of the chickenpox vaccine.

Alternative Names

Varicella; Chicken pox

Causes

Chickenpox is caused by the varicella-zoster virus. It is a member of the herpesvirus family. The same virus also causes shingles in adults.

Chickenpox can be spread very easily to others from 1 to 2 days before blisters appear until all the blisters have crusted over. You may get chickenpox:

From touching the fluids from a chickenpox blister
If someone with the disease coughs or sneezes near you

Most cases of chickenpox occur in children younger than age 10. The disease is most often mild, although serious complications may occur. Adults and older children get sicker than younger children in most cases.

Children whose mothers have had chickenpox or have received the chickenpox vaccine are not very likely to catch it before they are 1 year old. If they do catch chickenpox, they often have mild cases. This is because antibodies from their mothers' blood help protect them. Children under 1 year old whose mothers have not had chickenpox or the vaccine can get severe chickenpox.

Severe chickenpox symptoms are more common in children whose immune system does not work well.

Symptoms

Most children with chickenpox have the following symptoms before the rash appears:

Fever
Headache
Stomach ache

The chickenpox rash occurs about 10 to 21 days after coming into contact with someone who had the disease. In most cases, a child will develop 250 to 500 small, itchy, fluid-filled blisters over red spots on the skin.

The blisters are most often first seen on the face, middle of the body, or scalp.
After a day or two, the blisters become cloudy and then scab. Meanwhile, new blisters form in groups. They often appear in the mouth, in the vagina, and on the eyelids.
Children with skin problems, such as eczema, may get thousands of blisters.

Most pox will not leave scars unless they become infected with bacteria that is made more likely by scratching.

Some children who have had the vaccine will still develop a mild case of chickenpox. In most cases, they recover much more quickly and have only a few poxes (fewer than 30). These cases are often harder to diagnose. However, these children can still spread chickenpox to others.

Exams and Tests

Your health care provider can most often diagnose chickenpox by looking at the rash and asking questions about the person's medical history. Small blisters on the scalp confirm the diagnosis in most cases.

Lab tests can help confirm the diagnosis, if needed.

Treatment

Treatment involves keeping the person as comfortable as possible. Here are things to try:

Avoid scratching or rubbing the itchy areas. Keep fingernails short to avoid damaging the skin from scratching.
Wear cool, light, loose bedclothes. Avoid wearing rough clothing, particularly wool, over an itchy area.
Take lukewarm baths using little soap and rinse thoroughly. Try a skin-soothing oatmeal or cornstarch bath.
Apply a soothing moisturizer after bathing to soften and cool the skin.
Avoid prolonged exposure to excessive heat and humidity.
Try over-the-counter oral antihistamines such as diphenhydramine (Benadryl), but be aware of possible side effects, such as drowsiness.
Try over-the-counter hydrocortisone cream on itchy areas.

Medicines that fight the chickenpox virus are available, but not given to everyone. To work well, the medicine should be started within the first 24 hours of the rash.

Antiviral medicines are not very often prescribed to otherwise healthy children who do not have severe symptoms. Adults and teens, who are at risk for more severe symptoms, may benefit from antiviral medicine if it is given early.
Antiviral medicine may be very important for those who have skin conditions (such as eczema or recent sunburn), lung conditions (such as asthma), or who have recently taken steroids.
Some providers also give antiviral medicines to people in the same household who also develop chickenpox, because they will most often develop more severe symptoms.

DO NOT give aspirin or ibuprofen to someone who may have chickenpox. Use of aspirin has been associated with a serious condition called Reye syndrome. Ibuprofen has been associated with more severe secondary infections. Acetaminophen (Tylenol) may be used.

A child with chickenpox should not return to school or play with other children until all chickenpox sores have crusted over or dried out. Adults should follow this same rule while considering when to return to work or be around others.

Outlook (Prognosis)

In most cases, a person recovers without complications.

Once you have had chickenpox, the virus often remains dormant or asleep in your body for your lifetime. About 1 in 10 adults will have shingles when the virus re-emerges during a period of stress.

Possible Complications

Rarely, infection of the brain has occurred. Other problems may include:

Reye syndrome
Infection of the heart muscle
Pneumonia
Joint pain or swelling

Cerebellar ataxia may appear during the recovery phase or later. This involves a very unsteady walk.

Women who get chickenpox during pregnancy can pass the infection to the developing baby. Newborns are at risk for severe infection.

When to Contact a Medical Professional

Contact your provider if you think that your child has chickenpox or if your child is over 12 months of age and has not been vaccinated against chickenpox.

Prevention

Because chickenpox is airborne and spreads very easily, even before the rash appears, it is hard to avoid.

A vaccine to prevent chickenpox is part of a child's routine vaccine schedule.

The vaccine often prevents the chickenpox disease completely or makes the illness very mild.

Talk to your provider if you think your child might be at high risk for complications and might have been exposed. Taking preventive steps right away may be important. Giving the vaccine early after exposure may still reduce the severity of the disease.

References

Centers for Disease Control and Prevention website. Vaccine information statement. Varicella (chickenpox) vaccine: what you need to know. www.cdc.gov/vaccines/hcp/vis/vis-statements/varicella.html. Updated August 6, 2021. Accessed September 13, 2023.

LaRussa PS, Marin M, Gershon AA. Varicella-zoster virus. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 280.

Wodi AP, Murthy N, Bernstein H, McNally V, Cineas S, Ault K. Advisory committee on immunization practices recommended immunization schedule for children and adolescents aged 18 years or younger - United States, 2022. MMWR Morb Mortal Wkly Rep. 2022;71(7):234-237. PMID: 35176011 pubmed.ncbi.nlm.nih.gov/35176011/.