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 in others they can 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.

Chickenpox (medically known as varicella) is caused by a virus called the varicella-zoster virus. It’s spread quickly and easily through the coughs and sneezes of someone who is infected.

Chickenpox is most common in children under 10. In fact, chickenpox is so common in childhood that 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 the spots have crusted over.

Chickenpox is most 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).

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.

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, for example:

• 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.

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.

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.

Chickenpox and shingles

One 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 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.