What is chickenpox?
Chickenpox (varicella) is a contagious illness that causes an itchy rash and red spots or blisters (pox) all over the body. Chickenpox can cause problems for pregnant women, newborns, teens and adults, and people who have immune system problems that make it hard for the body to fight infection.
Chickenpox usually isn't a serious health problem in healthy children. But a child with chickenpox needs to stay home from school. And you may need to miss work in order to care for your child.
After you have had chickenpox, you aren't likely to get it again. But the virus stays in your body long after you get over the illness. If the virus becomes active again, it can cause a painful viral infection called shingles.
What causes chickenpox, and how is it spread?
Chickenpox is caused by the varicella-zoster virus. It can spread easily. You can get it from an infected person who sneezes, coughs, or shares food or drinks. You can also get it if you touch the fluid from a chickenpox blister.
A person who has chickenpox can spread the virus even before he or she has any symptoms. Chickenpox is most easily spread from 2 to 3 days before the rash appears until all the blisters have crusted over.
You are at risk for chickenpox if you have never had the illness and haven't had the chickenpox vaccine. If someone you live with gets chickenpox, your risk is even higher because of the close contact.
What are the symptoms?
The first symptoms of chickenpox usually develop about 14 to 16 days after contact with a person infected with the virus. Most people feel sick and have a fever, a decreased appetite, a headache, a cough, and a sore throat. The itchy chickenpox rash usually appears about 1 or 2 days after the first symptoms start.
After a chickenpox red spot appears, it usually takes about 1 or 2 days for the spot to go through all its stages. This includes blistering, bursting, drying, and crusting over. New red spots will appear every day for up to 5 to 7 days.
In most cases, you or your child can go back to work, school, or daycare when you or your child feels well enough. But guidelines about when to return to work or school vary from province to province. Talk to your doctor about when you or your child can return to work, school, or daycare.
How is chickenpox diagnosed?
Your doctor will ask you about your symptoms and will examine you. This usually gives your doctor enough information to find out if you have chickenpox.
A healthy child with chickenpox symptoms may not need to visit a doctor. You may be able to describe your child's symptoms to the doctor over the phone.
Teenagers, adults, pregnant women, and people with health problems need to see a doctor for chickenpox. This is especially important for pregnant women, since chickenpox during pregnancy can cause birth defects or serious newborn infection.
How is it treated?
Most healthy children and adults need only home treatment for chickenpox. Home treatment includes resting and taking medicines to reduce fever and itching. You also can soak in oatmeal baths to help with itching.
People with long-term diseases or other health problems may need more treatment for chickenpox. They may need immunoglobulin treatment (IG) or antiviral medicine. Your doctor can give you these soon after you are exposed to the virus to help you feel better sooner.
How can you prevent chickenpox?
You can prevent chickenpox with the chickenpox vaccine. Children get the chickenpox vaccine as part of their routine immunizations.
The varicella-zoster virus, one of the herpes viruses, causes chickenpox infection. The same virus that causes chickenpox also causes shingles (herpes zoster).
How it is spread
The chickenpox virus can spread easily from one person to another. It most often spreads through the respiratory tract, such as mucous membranes of the mouth and nose. You also can get chickenpox through the air from an infected person's sneezing or coughing. Less often, chickenpox is spread when fluid from a chickenpox blister gets on your skin.
In rare cases, a person can get chickenpox from the fluid of shingles blisters.
The first symptoms of chickenpox include:
- A fever of 38°C (100.4°F) to 39.4°C (102.9°F).
- Feeling sick, tired, and sluggish.
- Little or no appetite.
- Headache and sore throat.
The first symptoms are usually mild in children, but they can be severe in teens and adults. These symptoms may continue throughout the illness.
About 1 or 2 days after the first symptoms of chickenpox appear, an itchy rash develops.
The first weeks after catching the virus
About 14 to 16 days after contact with a person infected with the virus, the first symptoms of chickenpox usually develop. Most people feel sick and have a fever, a decreased appetite, a headache, a cough, and a sore throat.
- Some children get the chickenpox rash without first having the early symptoms.
- Babies 6 months old and younger may have some protection against chickenpox from antibodies passed on by their mothers. So if they are infected with the virus, they may not have many symptoms.
- People with weak immune systems may get the first symptoms of chickenpox sooner than the usual 14 to 16 days after exposure.
Chickenpox is most contagious from 2 to 3 days before the rash appears until all the blisters have crusted over.
The chickenpox rash
The chickenpox rash usually appears on the upper body about 1 or 2 days after the first symptoms start. The trunk usually is most affected, and the arms and legs the least. The rash also may spread to the scalp, face, nose, and mouth. In rare cases, it spreads into the eyelid lining (conjunctiva), into the clear covering over the eye (cornea), inside the throat, or into the genital area.
It takes about 1 or 2 days for a chickenpox red spot (macule) to go through all its stages:
- Red or swollen spots or bumps appear and turn into blisters that are filled with clear or cloudy fluid and that look like pimples.
- The blisters break open, often leaking fluid.
- A dry crust forms over the broken blisters as they heal.
Skin infection is the most common complication for children under age 5. Skin infection can form after the rash is scratched. Scratching allows bacteria from the skin or under the fingernails to get into a chickenpox blister. The infection can become serious if it isn't treated. An infected blister also may leave a scar.
Some people also are at increased risk of more serious problems from chickenpox. This higher-risk group includes newborns, teenagers, adults—especially pregnant women—and those who have weak immune systems.
Although you become immune to the chickenpox virus after you have had chickenpox, the virus will still be in your body. The virus can later cause shingles (herpes zoster), usually when you are an older adult. About 1 in 5 people who have chickenpox will later get shingles.footnote 1 The shingles vaccine can help prevent shingles or make shingles less painful.
What Increases Your Risk
You are at risk for chickenpox if you have not had chickenpox or the vaccine and you:
- Live with someone who has chickenpox.
- Are indoors for more than 1 hour with someone who has chickenpox.
- Are in the hospital and share a room with someone who later gets chickenpox or are cared for by a staff member who later gets chickenpox.
- Have a weak immune system.
After you have had chickenpox or the vaccine, you become immune to the virus. It is possible that you may have a slight reaction after reexposure, such as a few spots and a slight fever. But you aren't likely to get chickenpox more than once.
When To Call
Call your doctor now if you or your child with chickenpox has:
- A severe headache or constant vomiting, sensitivity to bright light, or unusual sleepiness or confusion. These may be signs of inflammation of the brain (encephalitis).
- Problems breathing or persistent coughing. These may be signs of varicella pneumonia.
- Red, warm, and sore skin, or if the chickenpox rash changes to bigger open sores. These may be signs of serious skin infection.
Call for an appointment with your doctor if:
- You are older than age 12, you aren't sure if you have ever had chickenpox or the vaccine, and you have been exposed to chickenpox.
- You or your child has a weak immune system and has been exposed to chickenpox.
- You are pregnant and have been exposed to chickenpox.
- You or your child has chickenpox and any of the following:
- A fever that lasts longer than 24 hours
- A fever that comes back after being gone for a couple of days.
- Severe itching that cannot be relieved by home treatment
- Chickenpox rash on the eyeball
- A rash that lasts longer than 2 weeks
If you are a teen or adult, are pregnant, or have a weak immune system, it's important to see your doctor as soon as you think you've been exposed to the chickenpox virus. Your doctor may want to give you a medicine that helps protect you from the virus.
A healthy child with chickenpox symptoms may not need to visit a doctor. You may be able to describe your child's symptoms to the doctor over the phone. Then your child won't have to leave the house and risk spreading the virus to others. But it's important to check with your doctor to find out if your child needs to be seen.
If you go to a doctor's office, ask if you need to take any precautions when you arrive to avoid spreading the infection. For example, office staff may take you directly to an examination room when you arrive, rather than have you wait in the lobby.
Examinations and Tests
Chickenpox usually can be diagnosed based on how the chickenpox rash looks. For a healthy child, describing the rash over the phone to a doctor (rather than visiting the office) may be all you need to do.
Anyone who is over age 12, or pregnant, or has a weak immune system needs to be checked by a doctor as soon as you suspect chickenpox. When given right away, treatment can help prevent serious complications. For more information, see When to Call a Doctor.
At the doctor's office, your doctor will ask you about your symptoms and will examine you. This usually gives your doctor enough information to find out if you have chickenpox.
Chickenpox during pregnancy
A woman who has had chickenpox early in her pregnancy may want to have her fetus checked for birth defects. This can be done with a fetal ultrasound during the second trimester.
Find out if you are immune
If you have never had chickenpox or the chickenpox vaccine, you have no immunity against the virus. This means that the virus can make you sick—you can get chickenpox.
If you need to make sure you're immune to the chickenpox virus, a viral test can tell you. It makes sense to get a viral test if you aren't sure you're immune and you:
- Plan to or can possibly become pregnant. Having chickenpox immunity prevents complications of chickenpox during pregnancy.
- Are more likely than normal to get severely ill from chickenpox or to have complications of chickenpox.
- Are required to prove chickenpox immunity for work or school.
Treatment for chickenpox depends on your age, your health, how long it's been since you were exposed to the virus, and your symptoms.
- A healthy child with chickenpox may need only home treatment to help relieve itching and monitor fever. For more information, see Home Treatment.
- Healthy teens and adults with chickenpox usually have more severe symptoms than children and are at higher risk for complications than healthy children. If you are older than age 12, are pregnant, or have a weak immune system, your doctor may want to give you a medicine or vaccine that helps protect you from the virus. For more information, see Medications. Home treatment measures can also help to make you more comfortable.
The chickenpox, or varicella, virus spreads easily from person to person. If you have never had chickenpox or the chickenpox vaccine, you have no immunity against the virus. This means that the virus can make you sick.
If you or your child is not immune, you can prevent chickenpox by getting the vaccine. It is recommended for:
- All healthy children 12 months of age and older who have not had chickenpox.
- Healthy people who aren't sure if they've had the vaccine or chickenpox as a child.
- Women who are planning to get pregnant but aren't pregnant yet.
For women who aren't immune, chickenpox and pregnancy can be a dangerous combination. Getting the vaccine when not pregnant prevents complications of chickenpox during pregnancy. Talk to your healthcare provider about the right timing for the vaccine.
You can help prevent chickenpox by avoiding close contact with people infected with the virus. This is even more important if you have a weak immune system. But the virus can spread from an infected person even before symptoms develop.
Prevent chickenpox after being exposed to the virus
If you have been in contact with a person who has chickenpox and aren't sure if you're immune, talk to your healthcare provider. Some provinces don't give the vaccine to people after they've been exposed to the virus.
If you can't have the chickenpox vaccine (for example, during pregnancy) a shot of antibodies (immunoglobulin) or an antiviral medicine may help delay or prevent the chickenpox.
For more information, see Medications.
Don't expose children to chickenpox
Before the chickenpox vaccine was available, families often had the virus for weeks at a time as it sickened one person, then the next. To "get it over with," some parents intentionally exposed their children to a child with chickenpox.
Now that the vaccine can protect against the virus, parents have a safer option than exposing their children to chickenpox. Do not expose a child to the chickenpox virus. Even young children can have serious (though rare) complications from the infection, including pneumonia or encephalitis.
Most healthy children, teens, and adults with chickenpox need only home treatment. But all teens and adults with chickenpox need to see a doctor. When given right away, treatment can help prevent serious complications.
If you have chickenpox, you don't need to stay in bed. But it's best to stay quiet and rest. Over-the-counter medicines can help relieve symptoms such as fever and itching.
Before you give medicine to your sick child, check with your child's doctor. Because of their small size, children are more sensitive than adults to the effects of some medicines. Use a measuring spoon or medicine cup to give liquid medicine to a child. Don't guess the amount or use a regular table spoon.
The chickenpox rash itches. Do what you can to control the itch and avoid scratching. Scratching the blisters may cause a skin infection, or scars may form after the blisters heal.
You can take steps to control itching, such as taking oatmeal baths, applying cool compresses, and taking antihistamines. Check with your child's doctor before giving your child antihistamines. Antihistamines are not recommended for children younger than 6 years.
Fever is your body's normal response to infection. A higher-than-normal temperature kills bacteria and viruses that cause illness. Fever medicines stop this natural process, so use one only when fever is causing discomfort.
You can help relieve a fever with over-the-counter medicine. Follow the package instructions carefully. If you give medicine to your baby, follow your doctor's advice about what amount to give. (Do not give aspirin to people younger than 20, because of the risk of Reye syndrome, a rare but serious problem).
Call your doctor if you or your child has a fever that lasts longer than 24 hours.
Prevent the spread of infection
In most cases, you or your child can go back to work, school, or daycare when you or your child feels well enough. But guidelines about when a child can return to school or daycare may vary from province to province. Talk to your doctor about when you or your child can return to work, school, or daycare. To help prevent spreading chickenpox, stay away from people who aren't immune.
Medicines for chickenpox can:
- Help make chickenpox less severe after you are exposed or have symptoms.
- Help relieve chickenpox itch, pain, and fever.
The right medicine depends on your health, age, how long it's been since you were exposed to the virus, and your symptoms.
Vaccination to prevent chickenpox
To prevent chickenpox (before you are exposed), most people can get the chickenpox vaccine.
Some people can't get the chickenpox vaccine. They include women who are pregnant and people who have ever had an anaphylactic reaction to gelatin, neomycin, or any other substance in the vaccine.
Medicines to help reduce the severity of chickenpox
- Immunoglobulins. Immunoglobulins (IG) help the body's immune system recognize and destroy harmful bacteria and viruses in the body, such as the varicella virus. Pregnant women (who are not immune to chickenpox), newborn babies and people who have certain immune system problems may need to get chickenpox IG soon after they are exposed to the virus. It can help prevent infection and help them feel better sooner.
- Antiviral medicine. Antiviral medicine, such as acyclovir, is usually used to treat adults who have weak immune systems. It's used after you start to have symptoms of chickenpox. Healthy children and adults usually don't need this medicine when they have chickenpox. It isn't known whether antiviral medicines reduce a person's chances of having complications of chickenpox.
Medicines to relieve pain and discomfort
After you have symptoms of chickenpox, you can take over-the-counter medicines to help relieve discomfort. These types of medicine are often used for chickenpox:
- Acetaminophen (such as Tylenol) or ibuprofen (such as Advil) to reduce pain and fever. Follow the package instructions carefully. The Canadian Paediatric Society recommends not giving ibuprofen (such as Advil or Motrin) to children with chickenpox. If you give medicine to your baby, follow your doctor's advice about what amount to give. Do not give aspirin to anyone younger than 18, because of the risk of Reye syndrome.
- Oral antihistamines (such as diphenhydramine) to relieve itching. Talk to your doctor before using any antihistamine lotions or creams on yourself or your child. And check with your child's doctor before giving antihistamine pills to your child. Antihistamines are not recommended for children younger than 6 years.
- Your doctor may prescribe antibiotics to you or your child if you get a skin infection from chickenpox blisters.
- Gershon AA (2009). Varicella-zoster virus. In RD Feigin et al., eds., Feigin and Cherry's Textbook of Pediatric Infectious Diseases, 6th ed., vol. 2, pp. 2077–2088. Philadelphia: Saunders Elsevier.
- American Academy of Pediatrics (2012).Varicella-zoster infections. In LK Pickering et al., eds., Red Book: 2012 Report of the Committee on Infectious Diseases, 29th ed., pp. 774–789. Elk Grove Village, IL: American Academy of Pediatrics.
Adaptation Date: 1/4/2023
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services