Chickenpox, also known as varicella, is a highly contagious infection caused by the varicella zoster virus (VZV). It causes an itchy, blister-like rash. Most people recover within 1–2 weeks, but some develop complications.

Chickenpox is a viral illness that causes a blister-like rash. The rash first appears on the face and trunk and then spreads throughout the body.

Among people who are not vaccinated, it is extremely contagious. Although chickenpox is not a life-threatening illness, it can sometimes cause complications.

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Chickenpox is most commonly a childhood illness. Before the chickenpox vaccine was introduced in 1995, most people in the United States caught chickenpox as children.

Today, some vaccinated people can still get chickenpox, as well as some people who are unvaccinated or immunocompromised.

Those vaccinated people who still get infected may develop milder symptoms. This is called breakthrough chickenpox.

Stages of chickenpox

Chickenpox develops in stages. Before the rash appears, there may be:

  • fatigue or a general feeling of being unwell (malaise)
  • fever that lasts 3-5 days and is usually less than 102 °F (39 °C ).
  • loss of appetite
  • Muscle or joint aches
  • cold-like symptoms such as a cough or runny nose
  • headache

After these symptoms, the following will happen:

  • An itchy rash will present on the face, body, or inside the mouth. The rash will develop in spots and sometimes can also appear on the eyelids or the genitals. The severity of the rash can vary.
  • The rash will develop into fluid-filled blisters that will turn cloudy. These blisters make take 3-5 days to heal. As there may be many blisters, some may heal sooner than others.
  • The blisters will become scabs. The scabs will fall off after about a week.

Symptoms in adults

Chickenpox symptoms in infected adults who did not get the disease as children may be similar to symptoms in children but they could be more severe. Those who are unvaccinated or immunocompromised are especially at risk.

Some adults may not develop a rash. If they do develop a rash, the rash may not spread in the same way. However, if they do get a rash, it may leave deeper marks and scars.

Adults are also more at risk for complications such as pneumonia.

The varicella-zoster virus (VZV) causes chickenpox.

This is an extremely contagious virus that belongs to the family of herpesviruses that also include herpes simplex virus types 1 and 2, Epstein-Barr virus, and others.

There are more than 100 viruses in the herpesvirus family. They mostly affect the skin, mucus membranes, nerves, and tissues.

Chickenpox is one of the most infectious diseases. People who have never had chickenpox, have never been vaccinated, or have a compromised immune system are at the highest risk of infection.

Transmission happens through direct contact between people through coughing or sneezing, or by air.

VZV can also cause another condition known as shingles or herpes zoster. A person can also get chickenpox if they come in contact with fluid either from someone’s chickenpox or shingles blister.

Chickenpox and a weakened immune system

The risks of contracting chickenpox and the development of complications are higher in a person with a weakened immune system.

A weakened immune system can result if a person:

  • is taking certain medications
  • has cancer
  • is undergoing treatment such as radio- or chemotherapy
  • has certain chronic conditions, such as lupus or rheumatoid arthritis
  • has other chronic illnesses such as uncontrolled diabetes, or heart, liver, or kidney failure

There is no cure for chickenpox, but it generally resolves within a week or two without treatment.

A doctor may prescribe medication or give advice on how to reduce symptoms of itchiness and discomfort, and also on how to prevent transmission of the infection.

The following are some treatments that may alleviate symptoms:

  • Pain-relieving drugs: Tylenol (acetaminophen) may help reduce high fever and pain when a person has chickenpox. But it is important to follow the instructions provided by the manufacturer and the person’s doctor. People should not use aspirin-containing products to treat chickenpox, as this can lead to complications. People should also avoid ibuprofen, as it could increase the risk of strep throat.
  • Avoiding dehydration: It is important to drink plenty of fluids, preferably water, to prevent dehydration, which can be a complication of chickenpox.
  • Sugar-free popsicles: These can help ease symptoms of mouth soreness if there are spots in the mouth. Avoid salty or spicy foods. If chewing is painful, soup might be a good option, as long as it is not too hot.
  • Reduce itching: Itching can become severe, but it is important to minimize scratching to reduce the risk of scarring. Things that can help include topical ointments, cool baths, or oral Benadryl tablets.

The following may also help prevent scratching:

  • keeping fingernails clean and as short as possible
  • placing mittens or even socks over a child’s hands when they go to sleep, so that any attempt at scratching during the night does not cut the skin
  • wearing loose clothing

A doctor may prescribe antiviral medication during pregnancy, for adults who get an early diagnosis, for newborns, and for those with a weakened immune system.

Acyclovir is one example of an antiviral medication that treats chickenpox. This works best if it is given within 24 hours of developing symptoms. It reduces the severity of symptoms but does not cure the disease.

There is no cure for chickenpox, but a vaccine is available for VZV. Today, the chickenpox vaccine is about 90% effective at preventing the disease for most people.

People should avoid close contact with people known to have chickenpox, avoid sharing objects with them, isolate any household members with chickenpox from others, and disinfect surfaces an infected person may have touched.

Types of chickenpox vaccines

There are two types of the VZV vaccine:

  • Varivax: This is only the chickenpox vaccine. Children get two shots, with the first dose between 12-15 months and a second time between 4-6 years. Anyone 12 months and older can get this vaccine. This includes adolescents and adults.
  • ProQuad: This is a combination vaccine that also contains vaccines for measles, mumps, and rubella. Healthcare professions call it MMRV. Children get this vaccine on the same schedule as Varivax, but it can only be given to children between 12 months and age 12.

Among unvaccinated people who develop chickenpox, a few people may have more severe symptoms. Adults are more susceptible to complications than children, but even in adults, they are rare.

Pregnant women, newborns, and infants up to 4 weeks old, as well as those with weakened immune systems, are more likely to experience complications.

If the following occurs, a person should contact a doctor:

  • Infection: If the skin around the spots and blisters becomes red and tender or sore, there may be a bacterial infection in the skin.
  • Breathing problems: If a person experiences breathing difficulties, they may be developing pneumonia.
  • Encephalitis: A person can develop an inflammation of the brain. Symptoms include confusion, sleepiness, behavior or personality changes, or seizures.
  • Reye’s syndrome: In rare cases, recovering children and teenagers will experience swelling of the liver and brain.
  • Bleeding: A person can experience a hemmorhage, which is a loss of blood from a ruptured blood vessel.
  • Sepsis: A person can get an infection in the blood, which is a life-threatening condition.

Chickenpox and pregnancy

People who are pregnant have a slightly higher risk of developing pneumonia from chickenpox. There is also a danger of passing the infection to the fetus.

If infection occurs during the first 20 weeks of pregnancy, there is a higher risk of congenital varicella syndrome. This can cause scarring in the fetus, as well as eye problems, brain drainage, and shortened arms or legs.

If the infection happens later in pregnancy, the virus can transmit directly to the fetus and the baby can be born infected.

If a person becomes exposed to varicella during pregnancy, it is important to talk to a doctor right away.

A doctor or nurse will know whether a child or adult has chickenpox by recognizing a person’s tell-tale rash and asking a few questions about their symptoms.

In cases when a person is not vaccinated and is not sure whether they have had chickenpox as a child, they can get a laboratory test to determine whether they did have the virus in the past.

People who have had chickenpox as children will not get the disease again. This is because they develop immunity to the virus. If a person who has been exposed to someone with chickenpox is not sure if they had the illness as a child, getting tested can help them know if they are at risk for getting the disease.

Another reason to get tested is to help a doctor distinguish the symptoms of chickenpox from other conditions with similar symptoms. One of those conditions may be shingles.

Shingles vs chickenpox

In some cases, a doctor may think that a person has shingles and not chickenpox. When a person has chickenpox and recovers, the virus stays in their body and becomes dormant. Later in life, in situations of low immunity, the virus can reactivate as shingles.

People who have active shingles cannot give other people shingles. However, they can infect others with chickenpox if those people have not already had the illness, are not vaccinated, or are immunocompromised.

Shingles symptoms

Shingles affects a person’s nerves. Usually, people will experience an intensely painful rash that looks like a patch of raised dots and follows the path of a nerve on one side of the body. This may be on the face or the trunk of the body, but may also occur in other areas.

The rash may be itchy. In addition, a person may also feel stabbing pain. Later, the rash will turn into fluid-filled blisters that crust over within several days.

When a person gets shingles, they may also get a fever or a headache. Additional symptoms may include nausea, diarrhea, upset stomach, and chills.

Shingles can also cause postherpetic neuralgia, which is pain from shingles lasting for at least three months after the blisters have gone. It can also cause neurological problems affecting the brain, spinal cord, and facial nerves.

A doctor may suspect a person has shingles instead of chickenpox if the person has had chickenpox before, is over the age of 50, under a lot of stress, or if they are immunocompromised. These are factors that may put a person at a higher risk for the condition.

Learn more about shingles.

Chickenpox is a contagious illness caused by the varicella-zoster virus (VZV) that causes a highly itchy rash. Historically, most people have gotten it in childhood. If people get it as adults, they may be at risk for more serious symptoms and complications.

Since 1995, most people in the U.S. have received a vaccine for chickenpox. There are two types of chickenpox vaccines, which usually are administered twice in a person’s childhood.

The vaccine prevents about 90% of infections in the U.S. Some infections may still occur among unvaccinated or immunocompromised people.

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