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Encyclopaedia


Chickenpox

Introduction

Chickenpox is a mild and common childhood illness that most children catch at some point.

It causes a rash of red, itchy spots that turn into fluid-filled blisters. They then crust over to form scabs, which eventually drop off.

Some children have only a few spots, but other children can have spots that cover the entire body. The spots are most likely to appear on the face, ears and scalp, under the arms, on the chest and stomach and on the arms and legs.

Read more about the symptoms of chickenpox and watch a slideshow of common childhood conditions to help you recognise if your child has it.

Chickenpox (medically known as varicella) is caused by a virus called the varicella-zoster virus. It's spread quickly and easily from someone who is infected.

Read more about the causes of chickenpox.

Chickenpox is most common in children under 10 years of age, although it can develop at any age. It is most common to catch chickenpox in winter and spring, particularly between March and May.

Chickenpox is so common in childhood that 90% of adults who grew up in the UK are immune (resistant) to the condition because they have had it before.

What to do

To prevent spreading the infection, keep children off nursery or school until all their spots have crusted over.

Chickenpox is infectious from one to two days before the rash starts, until all the blisters have crusted over (usually five to six days after the start of the rash).

If your child has chickenpox, try to keep them away from public areas to avoid contact with people who have not had it, especially people who are at risk of serious problems, such as newborn babies, pregnant women and anyone with a weakened immune system (for example, people having cancer treatment or taking steroid tablets).

Read more about what you need to do to stop chickenpox spreading.

Chickenpox treatment

Chickenpox in children is considered a mild illness, but expect your child to feel pretty miserable and irritable while they have it.

Your child is likely to have a fever at least for the first few days of the illness. The spots can be incredibly itchy.

There is no specific treatment for chickenpox, but there are pharmacy remedies which can alleviate symptoms, such as paracetamol to relieve fever and calamine lotion and cooling gels to ease itching.

In most children, the blisters crust up and fall off naturally within one to two weeks.

Read more about chickenpox treatments.

When to see a doctor

For most children, chickenpox is a mild illness that gets better on its own.

But some children can become more seriously ill with chickenpox. They need to see a doctor.

Contact your GP straight away if your child develops any abnormal symptoms, such as:

  • if the blisters on their skin become infected
  • if your child has a pain in their chest or has difficulty breathing

Chickenpox in adults

Chickenpox may be a childhood illness, but adults can get it too. Chickenpox tends to be more severe in adults than children, and adults have a higher risk of developing complications.

As with children, adults with chickenpox should stay off work until all the spots have crusted over. They should seek medical advice if they develop any abnormal symptoms, such as infected blisters.

Adults with chickenpox may benefit from taking antiviral medicine if treatment is started early in the course of the illness. Read more about antivirals in the treatment of chickenpox.

Who's at special risk?

Some children and adults are at special risk of serious problems if they catch chickenpox. They include:

  • pregnant women
  • newborn babies
  • people with a weakened immune system

These people should seek medical advice as soon as they are exposed to the chickenpox virus or they develop chickenpox symptoms.

They may need a blood test to check if they are immune (protected from) chickenpox.

Read more about immunity testing and the diagnosis of chickenpox in people at special risk.

Chickenpox in pregnancy

Chickenpox occurs in approximately three in every 1,000 pregnancies. It can cause serious complications for both the pregnant woman and her baby. See Chickenpox - complications for further information on what to do if you are exposed to chickenpox during pregnancy.

Chickenpox and shingles

Once you have had chickenpox, you usually develop antibodies to the infection and become immune to catching it again. However, the virus that causes chickenpox, the varicella-zoster virus, remains dormant (inactive) in your body's nerve tissues and can return later in life as an illness called shingles.

It is possible to catch chickenpox from someone with shingles, but not the other way around.

Read more about shingles.

Is there a vaccine against chickenpox?

There is a chickenpox vaccine but it is not part of the routine childhood vaccination schedule. The vaccine is only offered to children and adults who are particularly vulnerable to chickenpox complications.

Read more about the chickenpox vaccine.

Can I get chickenpox more than once?

Yes, there is some evidence to suggest that it may be possible to catch chickenpox a second time although it has very rarely been proven.

How might someone get chickenpox again?

There are several theories that could explain how someone might get chickenpox more than once. Some examples are explained below.

  • Many medical professionals believe that the person’s condition was misdiagnosed first time around, and that they had another condition with similar symptoms.
  • There may be a genetic link. In the US studies mentioned above, around half of the people who reported having chickenpox before said that other members of their family had also had chickenpox more than once.
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Symptoms

The most commonly recognised symptom of chickenpox is a spotty, blistering red rash that can cover the entire body. However, even before the rash appears, you or your child may experience some mild flu-like symptoms. These symptoms may include:

  • nausea (feeling sick)
  • a high temperature (fever) of 38C (100.4F) or over 
  • aching, painful muscles
  • headache
  • generally feeling unwell
  • loss of appetite

These flu-like symptoms, especially the fever, tend to be worse in adults than in children.

Chickenpox spots

Shortly after these initial flu-like symptoms, an itchy rash appears  Some people may only have a few spots, but others are covered from head to toe.

The spots normally appears in clusters and tend to be:

  • behind the ears
  • on the face
  • over the scalp
  • under the arms
  • on the chest and stomach
  • on the arms and legs

But the spots can be anywhere on the body, even inside the ears and mouth, on the palms of the hands, soles of the feet and inside the nappy area.

Although the rash starts as small, itchy red spots these develop a blister on top and become intensely itchy after 12-14 hours.

After a day or two , the fluid in the blisters gets cloudy, and they begin to dry out and crust over. After one to two weeks, the crusting skin will fall off naturally.

New spots can keep appearing in waves for three to five days after the rash begins. Therefore different clusters of spots may be at different stages of blistering or drying out.

Read more about how to ease the itchiness and other symptoms of chickenpox in our section on chickenpox treatments.

Find out what you can do to stop chickenpox spreading.

Unusual symptoms

Most healthy children (and adults) recover from chickenpox with no lasting ill-effects simply by resting, just as with a cold or flu.

But some children and adults are unlucky and have a more severe bout than usual.

Contact your GP straight away if you or your child develop any abnormal symptoms, such as:

  • if the skin surrounding the blisters becomes red and painful
  • if you or your child start to get pain in the chest or have difficulty breathing
  • signs of dehydration, such as fewer wet nappies, drowsiness and cold hands and feet

In these cases, prescription medicine, and possibly hospital treatment, may be needed.

Read more about chickenpox complications.

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Causes

Chickenpox is caused by the varicella-zoster virus. You catch it by coming into contact with someone who is infected.

Chickenpox is a very contagious infection. About 90% of people who have not previously had chickenpox will become infected when they come into contact with the virus.

How you catch the virus

The chickenpox virus is spread most easily from someone who has the rash. The blisters are very itchy and break open easily, which can contaminate surfaces or objects. The virus may then be transferred by touching the surface or object, then touching your face.

The virus is also contained in the millions of tiny droplets that come out of the nose and mouth of an infected person when they sneeze or cough.This can also contaminate surfaces or objects.

It normally takes 14 days for the symptoms of chickenpox to show after you have come into contact with the virus.  However, this can vary from person to person – from as little as 7 days, up to 21 days. This is called the ‘incubation period’.

Someone who has the chickenpox virus is most infectious from one to two days before the rash appears until all the blisters have crusted over. This is usually five to six days after the start of the rash.

Shingles

If you have not had chickenpox before, it is possible to catch chickenpox from someone who has shingles (an infection caused by the same virus). However, it is not possible to catch shingles from someone who has chickenpox.

See the topic about Shingles for more information on this condition.

Have you been exposed to chickenpox?

As a rule of thumb, you have been exposed to chickenpox if you have:

  • been in the same room as an infected person for 15 minutes
  • had face-to-face contact with an infected person
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Diagnosis

You or your child should not usually need any medical tests to diagnose chickenpox. You can be pretty sure that it is chickenpox if there are the key symptoms of a mild fever followed by an itchy rash, blisters and scabs.

Chickenpox spots are usually distinctive enough to distinguish from other rashes, although occasionally they can be easily confused with other conditions that affect the skin, such as insect bites or scabies (a contagious skin condition that causes intense itching).

Watch this slideshow of common skin conditions to see what scabies, insect bites and other common skin rashes look like, so that you don't confuse them with chickenpox.

If you're still uncertain about what is causing the symptoms, your GP can carry out a simple blood test to identify the virus.

When to contact your GP

1. See your GP if you're not sure whether you or your child have chickenpox.

2. Contact your GP urgently if you have been in contact with someone who has chickenpox or you have chickenpox symptoms and:

  • you are pregnant
  • you have a weakened immune system (the body’s defence system)
  • your baby is less than four weeks old

Chickenpox in these instances can cause serious complications if left untreated. It is essential to seek medical advice so that you can receive any necessary treatment.

3. Contact your GP if you have chickenpox and are breastfeeding. They can advise about whether you should continue breastfeeding your baby.

Having a blood test

Once you have contacted your GP, you may need a test to see if you're already immune from chickenpox.

If you have had chickenpox in the past, then it is extremely unlikely that you will develop chickenpox for a second time. If you've never had chickenpox, or you're unsure whether you've had it, then you may need an immunity test.

This is a blood test that checks whether you are producing the antibodies to the chickenpox virus.

If your blood test result shows that you have the antibodies, you'll be naturally protected from the virus. If you don't have the antibodies, then you'll need to be monitored closely to see if you develop chickenpox symptoms. If you do, you may require further treatment.

Read more about chickenpox treatment.

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Treatment

There is no cure for chickenpox, and the virus usually clears up by itself without any treatment. However, there are ways of easing the itch and discomfort, and there are important steps you can take to stop chickenpox spreading.

Painkillers

If you or your child is in pain, or has a fever (high temperature), you can give them a mild painkiller, such as paracetamol.  These are available over the counter in pharmacies. Always read the manufacturer’s dosage instructions.

Paracetamol is the preferred painkiller for treating the associated symptoms of chickenpox. This is due to a very small risk of non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen causing adverse skin reactions during chickenpox.

Avoid giving your child ibuprofen if they have asthma or a history of stomach problems. If you're not sure whether ibuprofen is suitable, check with your GP or pharmacist. If your child is younger than three months old, you should always speak to your GP before giving your child any kind of pain relief.

If you're pregnant and need to take painkillers, then paracetamol is the first choice. You can use it at any stage of pregnancy. Only take ibuprofen during the second trimester (weeks 14-27 of the pregnancy).

If you're pregnant and have chickenpox, you should visit your GP as soon as possible. You may need to have antiviral medicine or immunoglobulin treatment to prevent your symptoms from getting worse (see below).

Keeping hydrated

It is important for children (and adults) with chickenpox to drink plenty of water to avoid dehydration. Sugar-free ice-lollies are a good way of getting fluids into children. They also help sooth a sore mouth that has chickenpox spots in it.

Avoid anything that may make your mouth sore, such as salty foods. Soup is usually easy to swallow as long as it is not too hot.

Stop the scratching

Chickenpox can be incredibly itchy, but it's important for children (and adults) to not scratch the spots so as to avoid future scarring.

One way of stopping scratching is to keep fingernails clean and short.You may also consider putting socks over your child's hands at night to stop them scratching the rash as they sleep.

If your child's skin is very itchy or sore, try using calamine lotion or cooling gels. These are available in pharmacies and are very safe to use. They have a soothing, cooling effect.

A stronger medicine called chlorphenamine can also help to relieve the itching. It's available from your pharmacist over the counter or it can be prescribed by your GP. Chlorphenamine is taken by mouth and is suitable for children over one year old.

Cool clothing

If your child has a fever, or if their skin is sore and aggravated, then dress them appropriately so that they don't get too hot or too cold. If you or your child has chickenpox, it is best to wear loose-fitting, smooth, cotton fabrics. This will help stop the skin from becoming sore and irritated.

If your child has chickenpox, you should avoid tepid sponging (when you try to cool them down by sponging them with cool water). This can make your child too cold, and it may cause shivering.

Stronger treatments

Antiviral medicine

Aciclovir is an antiviral medicine that is sometimes given to people with chickenpox:

Aciclovir may be prescribed to:

  • pregnant women
  • adults, if they visit their GP within 24 hours of the rash appearing
  • newborn babies
  • people with a weakened immune system (the body’s defence system)

Aciclovir ideally needs to be started within 24 hours of your rash appearing. It does not cure chickenpox, but does make the symptoms less severe. You will normally need to take this medicine five times a day, for seven days.

If you are taking aciclovir, make sure you drink plenty of fluids.  Side effects are rare but can include nausea (feeling sick) and diarrhoea.

Immunoglobulin treatment

Immunoglobulin is a solution of antibodies that is taken from healthy donors. Varicella-zoster immunoglobulin (VZIG) contains antibodies to the chickenpox virus.

Immunoglobulin treatment is given by injection. It is not used to treat chickenpox but to protect people who are at high risk of developing a severe chickenpox infection. This includes:

  • pregnant women
  • newborn babies
  • people with weakened immune systems

In the case of pregnant women, immunoglobulin treatment also reduces the risk of the unborn baby becoming infected.

As the supply of VZIG is limited, it will only be considered if someone at high risk has:

  • been significantly exposed to the virus - significant exposure could be face-to-face contact with someone who has chickenpox
  • been in the same room with someone who has chickenpox for 15 minutes
  • had a blood test to confirm that they've not had chickenpox before

In some cases, newborn babies may be given immunoglobulin without being tested for antibodies first.

Aspirin alert

Never give your child aspirin if you suspect or know that they have chickenpox.

Children with chickenpox who take aspirin can develop a potentially fatal condition called Reye's syndrome, which causes severe brain and liver damage.

Speak to your GP or pharmacist if you are not sure which medicines to give your child.

Read more about Reye’s syndrome.

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Complications

Complications of chickenpox are rare in healthy children. The most common complication is when the rash of blisters becomes infected with bacteria.

A sign that the blisters have become infected is when the surrounding skin becomes red and sore.

If you think that your child's blisters have become infected, contact your GP as the child may require a course of antibiotics.

The people who are most at risk of developing chickenpox complications are:

  • adults
  • pregnant women
  • babies less than four weeks old
  • people with a suppressed immune system 

Adults

Chickenpox can be more serious in adults than in children. Adults with the virus are more likely to be admitted into hospital. Approximately 5-14% of adults with chickenpox develop lung problems, such as pneumonia. If you smoke, the risk of you developing lung problems is much greater.

Although it is more serious in adults, most people will still make a full recovery from the chickenpox virus.

Pregnant women

If you are pregnant, chickenpox can occasionally cause complications.

For example, your risk of developing pneumonia is slightly higher if you are pregnant, especially if you smoke. The further you are into your pregnancy, the more serious the risk of pneumonia tends to be.

If you get chickenpox while you are pregnant, the risk to your unborn baby is small, but significant.

If you are infected with chickenpox during the first 28 weeks of your pregnancy, there is a risk that your unborn baby could develop a condition known as fetal varicella syndrome (FVS).

This syndrome is rare, and the risk of it occurring in the first 12 weeks of pregnancy is less than 1%. Between 13 and 20 weeks, the risk is 2%.

There have only been a few reports of FVS due to an infection from weeks 20 to 28 of pregnancy, and the risk is thought to be much less than 1%.

Fetal varicella syndrome can cause serious complications including:

  • scarring
  • eye defects, such as cataracts
  • shortened limbs
  • brain damage

It is possible that your baby may be born prematurely (before week 37 of the pregnancy).

If you are infected with chickenpox seven days before or seven days after giving birth, your newborn baby may develop a more serious type of chickenpox. In a few severe cases, this form of chickenpox can be fatal.

See your GP urgently if you are pregnant or have given birth in the last seven days and think you may have chickenpox, or if you are exposed to someone who has chickenpox.

People with a weakened immune system

The immune system is the body's way of defending itself against disease, bacteria and viruses.

If your immune system is weak or does not work properly you are more susceptible to developing infections such as chickenpox.  This is because your body produces fewer antibodies to fight off the infection.

You may have a weakened immune system if you take immunosuppressive medication.  Immunosuppressive medication such as steroid tablets may be used if, for example, you have an inflammatory condition such as rheumatoid arthritis, lupus or certain blood conditions.

If you have a weakened immune system, you are also more at risk of developing complications from chickenpox. These complications include:

See your GP urgently if you have a weakened immune system and you have been exposed to the chickenpox virus.  

For more information, read about how to stop the spread of chickenpox.

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Prevention

If your child has chickenpox, you should inform your child's school or nursery and keep them at home while they are infectious, which is until the last blister has burst and crusted over. This usually takes five or six days after the rash begins.

If you have chickenpox, stay off work and at home until you are no longer infectious.

If either you or your child has chickenpox, it is also best for you, or them, to avoid contact with:

  • pregnant women
  • newborn babies
  • anyone who has a weak immune system (the body’s defence system), such as people who are having chemotherapy (a treatment for cancer) or taking steroid tablets

If you or your child has recently been exposed to the chickenpox virus, you may not be able to visit friends or relatives in hospital. Telephone the ward to check first.

Travelling on a plane

If you or your child have chickenpox, you may not be allowed to fly until six days after the last spot has appeared.

You and your child should be safe to fly once you are past the infectious stage and all of the blisters have crusted over.  But it is best to check the policy of your airline first. You should inform the airline as soon as chickenpox is diagnosed.

It is also important to let your travel insurer know if you or your child have chickenpox. You need to make sure that you will be covered if you have to delay or cancel your holiday, or if you need to extend your stay until your child is well enough to fly home.

Stop the virus spreading

Chickenpox can sometimes be spread through contact with objects that have been infected with the virus, such as children's toys, bedding or clothing.

If someone in your household has chickenpox, you can help stop the virus spreading by wiping any objects or surfaces with a sterilising solution and make sure that any infected clothing or bedding is washed regularly.

Vaccination

There is a chickenpox vaccine that is used to protect people who are most at risk of a serious chickenpox infection or of passing the infection on to someone who is at risk.

People who may be considered for vaccination include:

  • healthcare workers who are not already immune - for example, a nurse who has never had chickenpox and who may pass it to someone they are treating if they become infected
  • people living with someone who has a weakened immune system - for example, the child of a parent receiving chemotherapy

The vaccine is not suitable for pregnant women. After having the vaccine you should avoid getting pregnant for three months. The vaccine is also not suitable for people with weakened immune systems.

Tips for parents

For practical advice on all aspects of parenting, read the Birth to five guide or Bump Baby and Beyond. They contain NHS-accredited information to help you and your child stay healthy.

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Q&A

What should I do if I'm pregnant and I've been near someone with chickenpox?

It depends on whether you’ve had chickenpox or not. Most pregnant women in the UK and Ireland have had chickenpox and are immune to the virus that causes it.

What if I haven’t had chickenpox?

You should get advice from your GP or midwife immediately, even if you have no rash or other symptoms, if:

  • you’re pregnant and you know that you haven’t had chickenpox, or you’re not sure, and
  • you’ve been near someone with chickenpox or shingles.

Rarely, chickenpox during pregnancy can cause complications both for the woman and her baby.

You should also get medical advice straightaway if:

  • you’re pregnant and you think you may have chickenpox, or
  • you develop any rash when you’re pregnant, including a rash that develops after contact with someone who has chickenpox or shingles.

Chickenpox and shingles

In some people, the chickenpox virus can become active again later in life, when it causes shingles.

If you’re not immune to the chickenpox virus, it’s possible to catch chickenpox from someone who has shingles. However, this risk is very small.

What if I have had chickenpox?

If you’ve already had chickenpox, it’s extremely unlikely that you will get it again.

How rare is chickenpox during pregnancy?

It’s rare to get chickenpox when you’re pregnant. In the UK, it’s estimated that about three in every 1,000 women (0.3%) catch chickenpox during pregnancy.

Most pregnant women are immune to chickenpox

Chickenpox mainly affects children. In the UK, more than 90% of pregnant women are immune to the virus that causes chickenpox, because they had the condition as a child.

If you were born and grew up in a tropical or subtropical area, you’re less likely to have had chickenpox as a child. Examples of these areas include India, Malaysia, the Philippines, Singapore and some areas of Thailand.

Complications are rare

If a pregnant woman does get chickenpox, complications are also rare. Most pregnant women who get chickenpox recover, with no adverse effects for the baby.

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Selected links

NHS Direct Wales link

Shingles

External link

Welsh Government: Birth to five

Bump Baby and Beyond

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The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.
Last Updated: 03/03/2015 11:10:59

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