Three Diseases Caused by Viruses How Do You Get Chicken Pox

About chickenpox

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 their entire body. These are most likely to appear on the face, ears and scalp, under the arms, on the chest and belly, and on the arms and legs.

Read more about the symptoms of chickenpox.

Chickenpox (known medically 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 the age of 10. In fact, chickenpox is so common in childhood that over 90% of adults are immune to the condition because they've had it before.

Children usually catch chickenpox in winter and spring, particularly between March and May.

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 1 to 2 days before the rash starts, until all the blisters have crusted over (usually 5 to 6 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 may not have 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 your child will probably feel pretty miserable and irritable while they have it.

Your child may have a fever 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 that can alleviate symptoms. These include 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.

When to see a doctor

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

However, some children can become more seriously ill with chickenpox and 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.

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 protected from (immune to) chickenpox.

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

Chickenpox in pregnancy

Chickenpox occurs in approximately 3 in every 1,000 pregnancies. It can cause serious complications for both the pregnant woman and her baby. See complications of chickenpox 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 inactive (dormant) in your body's nerve tissues and can return later in life as an illness called shingles.

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

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.

The recommended 2 doses of the vaccine is estimated to offer 98% protection from chickenpox in children and 75% protection in adolescents and adults.

So it may be possible to develop the infection after vaccination. Similarly, there is a chance that someone who has received the vaccine could develop chickenpox after coming in close contact with a person who has shingles.

Symptoms of chickenpox

The most commonly recognised chickenpox symptom is a spotty, blistering red rash that can cover the entire body.

Chickenpox spots

The spots normally appear in clusters and tend to be:

behind the ears
on the face
over the scalp
on the chest and belly
on the arms and legs

However, 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 about 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 1 to 2 weeks, the crusting skin will fall off naturally.

New spots can keep appearing in waves for 3 to 5 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.

Feeling unwell

Before the rash appears, you or your child may have some mild flu-like symptoms, including:

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 more common and worse in adults than in children.

Unusual symptoms

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

However, some children and adults are unlucky and have a more severe bout.

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

the skin surrounding the blisters becoming red and painful
pain in the chest or difficulty breathing
signs of dehydration, such as fewer wet nappies, drowsiness and cold hands and feet

In cases such as this, prescription medicine or hospital treatment may be needed.

Read more about chickenpox complications.

Causes of chickenpox

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. Around 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 when an infected person coughs or sneezes. 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 with chickenpox is most infectious from 1 to 2 days before the rash appears, until all the blisters have crusted over. This usually takes 5 to 6 days from the start of the rash.

Read more about the diagnosis of chickenpox and how to stop chickenpox spreading.

Shingles

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

Diagnosing chickenpox

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, with blisters and scabs.

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

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

Find your local GP surgery.

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 4 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, 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, 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, you'll need to be monitored closely to see if you develop chickenpox symptoms. If you do, further treatment may be needed.

Treating chickenpox

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 your child is in pain or has a high temperature (fever), you can give them a mild painkiller, such as paracetamol (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 3 months old, you should always speak to your GP before giving your child any kind of pain relief.

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

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.

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 to soothe a sore mouth that has chickenpox spots in it.

Avoid anything that may make the mouth sore, such as salty foods. Soup is 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, to avoid future scarring.

One way of stopping scratching is to keep fingernails clean and short. You can also put 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 1 year old.

Cool clothing

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

If your child has chickenpox, avoid sponging them down with cool water. This can make your child too cold and may make them shiver.

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)

Ideally, aciclovir needs to be started within 24 hours of the rash appearing. It does not cure chickenpox, but it makes the symptoms less severe. You normally need to take the medicine as tablets 5 times a day for 7 days.

If you are taking aciclovir, make sure you drink plenty of fluids. Side effects are rare, but can include nausea 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 a high-risk person 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 for 15 minutes with someone who has chickenpox
had a blood test to confirm that they've not had chickenpox before

In some cases, newborn babies may be given immunoglobulin treatment without having a blood test first.

Read more about the complications of chickenpox.

Complications of chickenpox

Complications of chickenpox are rare in healthy children. The most common complication is where the blisters become 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 need a course of antibiotics.

Other complications in children

Very rarely, chickenpox can lead to more serious complications involving the nervous system (brain and spinal cord) in children.

These include infections of the brain (encephalitis), the protective membranes around the brain (meningitis) or part of the brain called the cerebellum (cerebellitis).

Signs of these problems can include:

a lack of energy
drowsiness
confusion
seizures (fits)
vomiting
severe headaches
a stiff neck
behavioural changes
problems with walking, balance or speech (ataxia)

Seek medical advice as soon as possible if your child develops any of these symptoms after having chickenpox.

At-risk groups

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

adults
pregnant women
babies under four weeks old
people with a weakened 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, your risk of developing lung problems is much higher.

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

Pregnant women

If you're pregnant, chickenpox can occasionally cause complications.

For example, your risk of developing pneumonia is slightly higher if you're 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're pregnant, there is also a small but significant risk to your unborn baby.

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 foetal varicella syndrome (FVS).

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

FVS can cause serious complications, including:

scarring
eye defects, such as cataracts
shortened limbs
brain damage

There are also other risks from catching chickenpox after week 20 of pregnancy.

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

If you are infected with chickenpox 7 days before or 7 days after giving birth, your newborn baby may develop a more serious type of chickenpox. In a few severe cases, this type of chickenpox can be fatal.

See your GP urgently if you're pregnant or have given birth in the last 7 days and you think you may have chickenpox, or if you've been exposed to someone who has chickenpox.

People with a weakened immune system

Your immune system is your 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're also more at risk of developing complications from chickenpox. These complications include:

pneumonia
blood poisoning (septicaemia)
meningitis

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

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

Preventing the spread of chickenpox

If your child has chickenpox,it is recommended that you inform their school or nursery, and keep them at home for 5 days.

If you have chickenpox, stay off work and at home until you're no longer infectious, which is until the last blister has burst and crusted over. This usually happens five or six days after the rash begins.

It is a good idea for anyone who has chickenpox to avoid contact with:

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

If you or your child have 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 6 days after the last spot has appeared.

You and your child should be safe to fly once you're past the infectious stage and all of the blisters have crusted over. However, it's best to check the policy of your airline first. Inform the airline as soon as chickenpox is diagnosed.

It is also important to let your travel insurer know if you or your child has chickenpox. You need to make sure that you'll 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 contaminated 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 making 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 chickenpox 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. Avoid getting pregnant for 3 months after having the vaccine. The vaccine is also not suitable for people with weakened immune systems.

How effective is the vaccine?