Chickenpox

Chickenpox is a mild and common illness that mostly affects children but can be caught at any age.

Causes 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.

Chickenpox is most common in children under the age of 10. Children usually catch chickenpox in winter and spring, particularly between March and May.

Symptoms of chickenpox

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

small red spots on child's back and arms
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

But, the spots can be anywhere on the body, including:

  • inside the ears and mouth
  • on the palms of the hands
  • soles of the feet
  • inside the nappy area.

The rash starts as small, itchy red spots. These develop a blister on top and become very itchy after about 12 to 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. So, different groups of spots may be at different stages of blistering or drying out.

Before chickenpox spots appear

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 symptoms, especially the fever, tend to be more common and worse in adults than in children.

Contacting your doctor about chickenpox

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

Chickenpox tends to be more severe in adults than children. Adults have a higher risk of developing complications.

Contact your GP practice if:

You or your child develop any abnormal symptoms, such as:

  • the skin around the blisters becomes hot, red and painful, (redness may be harder to see on brown or black skin)
  • pain in the chest or difficulty breathing
  • signs of dehydration, such as fewer wet nappies, drowsiness and cold hands and feet
  • blisters on their skin become infected
  • any of your or your child’s symptoms suddenly get worse

or

You have been in contact with someone who has chickenpox, or you have chickenpox symptoms and:

  • you are pregnant or have given birth in the last 7 days
  • you have a weakened immune system (the body’s defence system)
  • your baby is less than 4 weeks old
  • you are breastfeeding

If your GP is closed, phone 111.

Contact your GP practice if:

  • you’re not sure if you or your child has chickenpox
  • you’re worried about your child

Tell the receptionist you think it might be chickenpox before going in to a GP practice.

Chickenpox treatment

There is no treatment for chickenpox. But, you can get remedies from your pharmacy that can help symptoms. These include:

  • paracetamol to help bring down a fever
  • calamine lotion and cooling gels to ease itching.

In most children, the blisters crust up and fall off naturally within 1 to 2 weeks.

Adults with chickenpox may be helped by taking antiviral medicine if its diagnosed early enough.

Stopping the spread of chickenpox

You should keep children off school or nursery until all their spots have crusted over. This will help stop chickenpox being spread.

Adults with chickenpox should stay off work until all the spots have crusted over.

Chickenpox is infectious from 1 to 2 days before the rash starts. It stops being infectious when all the blisters have crusted over. This happens usually 5 to 6 days after the start of the rash.

If you or your child has chickenpox, try to keep them away from public areas. This will help them avoid contact with people who may not have had it.

You should especially stay away from people who are at risk of serious problems, such as:

  • newborn babies
  • pregnant women
  • anyone with a weakened immune system, (for example people having cancer treatment or taking steroid tablets)

Who’s at higher risk from chickenpox?

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 speak to their GP 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.

Chickenpox in pregnancy

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

Chickenpox occurs in approximately 3 in every 1,000 pregnancies.

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 get 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.

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.

Chickenpox and shingles

Once you have had chickenpox, you usually develop antibodies to the infection and become immune to catching it again.

But, the virus that causes chickenpox, the varicella-zoster virus, stays inactive in your body’s nerve tissues. This can come back later in life as an illness called shingles.

It’s 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.

Only children and adults who are more vulnerable to the complications of chickenpox will get offered the vaccine.

It may be possible to develop the infection after vaccination. There is also a chance that someone who has had the vaccine could develop chickenpox after coming into close contact with a person who has shingles.


Last updated:
25 June 2024