Patient education: Chickenpox prevention and treatment (Beyond the Basics)

CHICKENPOX OVERVIEW — Many people remember either having chickenpox or seeing it on someone else. The itchy rash caused by varicella, the chickenpox virus, is hard to miss. Before the vaccine became available, more than 90 percent of people had the infection by the time they were 15 years old.

Today, thanks to the advent of the varicella vaccine, chickenpox is relatively rare. This article will discuss the prevention and treatment of chickenpox.

Shingles, a painful rash caused by the reactivation of the chickenpox virus in people who were previously infected with chickenpox, is discussed separately. (See "Patient education: Shingles (Beyond the Basics)".)

CHICKENPOX PREVENTION — The chickenpox vaccine protects against infection in 80 to 90 percent of those who are vaccinated. People who do not develop full protection from the vaccine may develop chickenpox after exposure. However, their illness is usually mild and causes a less severe rash and often no fever.

Vaccination in children — In the United States, the varicella vaccine is recommended for all children at 12 through 15 months of age. A second dose is recommended at 4 to 6 years of age. The second dose may be administered earlier than age 4 years (for example, during a varicella outbreak); for such children <13 years, the two doses should be given at least three months apart. The vaccine may be given in a formulation that combines vaccines for measles, mumps, rubella, and varicella (MMRV, ProQuad). The varicella vaccine is not needed if a child is infected with chickenpox before being vaccinated. (See "Vaccination for the prevention of chickenpox (primary varicella infection)".)

Vaccination in adults — Most adults have not been given the varicella vaccine because they already had the infection in childhood, prior to the availability of vaccine in 1995. People who had chickenpox in the past are immune to varicella infection.

In contrast, adults who do not have immunity to chickenpox can benefit from being vaccinated. In fact, experts recommend varicella vaccination for adults without immunity, especially those who are at risk of exposure to chickenpox and those who are in contact with people who are at risk for severe chickenpox infection. This includes:

●Healthcare workers

●Those who are in close contact with people with a compromised immune system (this includes transplant recipients and people with HIV)

●Teachers of young children

●Daycare employees

●Susceptible young adults in colleges, military bases, or correctional facilities

●International travelers

●Women of childbearing age; however, women who are pregnant or plan to become pregnant soon should not receive the varicella vaccine.

If you are at risk for chickenpox but are unsure whether you have had the infection, you can have a blood test to check for immunity to varicella.

To be fully vaccinated, adults and children 13 years and older need two doses of the varicella vaccine, given at least four weeks apart.

Chickenpox vaccine precautions — The varicella vaccine contains a live virus, so it is not recommended for people with a compromised immune system or moderate to severe illness. In addition, the vaccine should not be given to people who have a severe allergy to neomycin or gelatin. (See "Allergic reactions to vaccines".)

Chickenpox vaccine side effects — The most common side effects of the varicella vaccine are redness or soreness at the injection site and a mild rash (usually about five spots). Contrary to popular belief, having the varicella vaccine does not increase the risk of developing shingles compared with natural infection.

CHICKENPOX SIGNS AND SYMPTOMS — The first symptoms of chickenpox usually include fever, feeling ill, sore throat, and loss of appetite.

The rash associated with the infection usually does not develop until a day after these symptoms begin. The chickenpox rash starts out as clusters of small, usually itchy spots that eventually blister and then pop (picture 1 and picture 2). After bursting, the blisters dry up, crust, and form scabs. The rash tends to form on the face, chest and back, or limbs, and new clusters of blisters continue to appear for a few days. (See "Clinical features of varicella-zoster virus infection: Chickenpox".)

How long does the rash last? — New blisters can develop throughout the body for about four days following the first sign of the rash. By day six, the blisters have completely scabbed over in most healthy people. The scabs then take a week or two to fall off, and may leave marks on the skin that take time to fade.

How does the infection spread? — If you have not had chickenpox and have not been fully vaccinated against varicella, you can become infected by breathing in airborne traces of the virus or touching an area of chickenpox rash on an infected person. Chickenpox is highly contagious, and an infected person can spread the infection even before developing a rash or showing any signs of being sick.

After being exposed to the varicella virus, you will begin to show symptoms about two weeks later. This period following exposure and preceding the onset of symptoms is called the incubation period. You can start spreading the virus during this period, starting two days before you show signs of a rash. You remain contagious until the last of the bumps have completely scabbed over. During this time, persons with chickenpox should avoid contact with others who might be susceptible. This may mean staying home, away from other children and adults.

Although chickenpox is generally a mild illness in children, susceptible adults and other high risk persons may become seriously ill after exposure. These risk groups include:

●Pregnant women

●Newborn babies

●People whose immune systems may be compromised, including those with HIV, or who have received an organ or bone marrow (stem cell) transplant

If you develop chickenpox, you should avoid contact with people at high risk for chickenpox complications until your lesions are scabbed over.

Catching chickenpox from someone with shingles — Children or adults who have never had chickenpox or the varicella vaccine can develop chickenpox by breathing in virus particles that are airborne following exposure to a person with widespread shingles. In addition, such individuals can get chicken pox from direct contact with skin lesions, although this is uncommon.

Can you catch chickenpox twice? — Most people who have had chickenpox do not develop chickenpox a second time. However, there are rare cases in which a person can develop chickenpox a second time. In some people, the virus can resurge later in life, causing a related condition called shingles, which is discussed elsewhere. (See "Patient education: Shingles (Beyond the Basics)".)

CHICKENPOX DIAGNOSIS — Healthcare providers can usually diagnose chickenpox just by looking at the rash. In some cases, additional tests may be used.

If you believe you or your child has the chickenpox, call your healthcare provider to find out if and when you should come in to be seen. In cases of possible chickenpox infection, healthcare providers must take steps to protect other patients. The clinician may need to make special arrangements so that you and/or your child do not infect other patients. For example, your healthcare provider may ask you to come in at the end of the day, when all the other patients have gone, and may ask you to enter the building through a different entrance than that normally used by patients.

Most children get over the chickenpox on their own with little or no treatment. If you believe your child has the chickenpox, check in with your healthcare provider to find out if your child should be evaluated in the clinic.

CHICKENPOX TREATMENT — There are two types of treatments for chickenpox: Those that ease its symptoms and those that target the infection. While most people can benefit from treatments to ease symptoms, not all people who get infected need treatment for the virus itself.

Managing symptoms — Simple treatments can usually ease fever and itchiness caused by chickenpox.

●Fever — To manage fever, you can take acetaminophen (sample brand name: Tylenol). (Note that children should not be given aspirin, as it can cause a dangerous condition called Reye syndrome). Children should be given acetaminophen according to their weight, rather than their age.

●Itching — To manage itching, you can take antihistamine medications, such diphenhydramine (sample brand name: Benadryl), which can make you sleepy, or loratadine (sample brand name: Claritin), which does not usually cause sleepiness. Skin treatments, like calamine lotion and oatmeal baths, may also help with itching, although there is scare scientific evidence that these remedies work.

Scratching the skin can cause a skin infection because bacteria hide beneath the fingernails. Scratching may also increase the chances of developing a scar. Fingernails should be clipped to reduce these risks.

Targeting the infection — A medication called acyclovir (sample brand name: Zovirax) or a medication similar to acyclovir (such as valacyclovir; sample brand name: Valtrex) can help shorten or combat the varicella infection if it is started within 24 hours of the rash developing. This medication is not necessary for everyone who develops chickenpox. However, it may be appropriate for people who are at risk of developing a more serious illness, such as:

●Adults

●Children older than 12 who are unvaccinated

●Children of any age with chronic lung problems (such as cystic fibrosis) or chronic skin conditions (such as eczema or atopic dermatitis)

●Children of any age who must take steroid medications (also called glucocorticoids) or aspirin on an ongoing basis

●Children or adults with a weakened immune system, including transplant recipients and people with HIV

Acyclovir can be taken in pill form or as an injection. It is generally well tolerated but can cause stomach upset or headache. (See "Treatment of varicella (chickenpox) infection".)

CHICKENPOX COMPLICATIONS — Most people who develop chickenpox fight off the infection without additional complications. Still, complications can arise, especially in adults and people with compromised immune systems. People who develop serious complications of chickenpox are usually hospitalized and treated with acyclovir.

Potential complications of chickenpox include:

●Skin infections

●Pneumonia, an infection of the lungs (see "Patient education: Pneumonia in adults (Beyond the Basics)").

●Encephalitis, inflammation of the brain

Children with a viral illness should be given acetaminophen for fever to avoid the complication of Reye syndrome, a rare condition that can cause severe brain and liver damage.

PREVENTING INFECTION AFTER EXPOSURE — People who have not had chickenpox or who have not been vaccinated are at risk of getting sick if exposed to a person with chickenpox. However, infection can be prevented.

If you or your child has been exposed to someone with chickenpox or shingles, call your healthcare provider immediately and ask what you should do. The varicella vaccine can be given, even after being exposed to the virus. If you cannot take the varicella vaccine, there is another injection (brand name: varicella immune globulin/VariZIG) that can temporarily protect you from becoming infected. (See "Post-exposure prophylaxis against varicella-zoster virus infection".)

CHICKENPOX DURING PREGNANCY — Coming down with chickenpox during pregnancy can lead to complications, such as pneumonia in the mother, or in rare cases, birth defects in the baby. Chickenpox is also very dangerous for newborn babies, so pregnant women who are not immune should contact their healthcare provider right away if they develop any signs of chickenpox or if they are exposed to someone with chickenpox or shingles.

Pregnant women who are exposed to the virus cannot receive the varicella vaccine, but they may need to take varicella immune globulin (brand name: VariZIG), an injection that can help to protect against infection. Pregnant women who get chickenpox need to be closely monitored for signs of infection and/or complications. (See "Varicella-zoster virus infection in pregnancy".)

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Chickenpox (The Basics)
Patient education: Shingles (The Basics)
Patient education: Acute cerebellar ataxia in children (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Shingles (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Vaccination for the prevention of chickenpox (primary varicella infection)
Treatment of varicella (chickenpox) infection
Clinical features of varicella-zoster virus infection: Chickenpox
Varicella-zoster virus infection in pregnancy
Varicella-zoster infection in the newborn
Epidemiology of varicella-zoster virus infection: Chickenpox
Post-exposure prophylaxis against varicella-zoster virus infection
Diagnosis of varicella-zoster virus infection

The following organizations also provide reliable health information.

●National Library of Medicine

     (www.nlm.nih.gov/medlineplus/healthtopics.html)

●National Institute of Allergy and Infectious Diseases

     (www.niaid.nih.gov/)

●Centers for Disease Control and Prevention (CDC)

     Toll-free: (800) 232-4636

(https://www.cdc.gov/vaccines/vpd/varicella/)

●National Foundation for Infectious Diseases

     Tel: (301) 656-0003

     (www.nfid.org/)

●The Children's Hospital of Philadelphia Vaccine Education Center

     (http://www.chop.edu/service/vaccine-education-center/)

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