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Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 4 minutes read

Chickenpox is a virus caused by the varicella-zoster virus. It is common among children but anyone can catch it at any age, but you can only catch it once. When adults get it, the symptoms are usually worse.

Chickenpox spreads in the same way as those responsible for colds, flu and other infectious diseases. The virus is contained within droplets of mucus and saliva which are released into the air via coughing or sneezing. These droplets also fall onto objects and surfaces which, when touched, enable the virus to be easily transferred to another person. You only need to be in the same space with an infected person for a short period of time for this virus to spread to you. It's 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.

There is an incubation period of 7 to 21 days before the symptoms of chickenpox make themselves known.

Chickenpox can be caught off someone with shingles but not vice versa.

What are the symptoms of chickenpox?

Sufferers develop flu-like symptoms before the rash appears. This is then followed by the rash which spreads over the entire body. It starts as a series of small red spots which then develop a blister on top. This blister causes intense itching.

The spots appear on the face and body, underneath the arms, inside the mouth and ears and on the soles of the feet and the palms of the hands.

The blistered spots then dry out and a crust forms on top which falls off after a couple of weeks. However, new clusters of spots usually appear after only a few days following the appearance of the rash so most people have spots which are either blistering or crusting over. The symptoms are worse in adults than children.

How is chickenpox diagnosed?

Chickenpox is characterised by a very typical rash which breaks out over the entire body, forms blisters and then dries out, resulting in scabs which eventually fall off so is usually easy to diagnose. See your doctor if you have a poorly functioning immune system, are pregnant or have a newborn baby - it is important that you do this as there is a risk of complications in these cases.

Chickenpox usually lasts a few weeks. People are infectious from a couple of days before the spots appear until after the spots have all crusted over (usually about five days later).

Are there any complications of chickenpox?

Once you’ve had the virus that causes chickenpox, it usually stays within the body and lies asleep. It can be reactivated later on in life, as shingles, when you are exposed to certain triggers like a lowered immune system, high stress, or certain treatments like chemotherapy.

In a few cases, chickenpox can cause serious complications such as an infection in the lungs or blood, an infection or inflammation in the brain, dehydration or bleeding complications.

Is chickenpox contagious?

Chickenpox is highly contagious. It can be spread just by being in the same room as someone with chickenpox and any close contact with an infected person. It will infect those who have never had chickenpox before.

It can take up to three weeks for chickenpox spots to show, from the time you were exposed to the virus. Because of this, anyone with chickenpox should avoid being around newborn babies, pregnant women and anyone with a weakened immune system.

What can I do to help?

You should drink plenty of fluids to avoid dehydration. Try and reduce the amount of scratching to prevent scarring. This can be done by cutting nails short, wearing gloves, and using cooling creams or antihistamine medicine to soothe the discomfort. You can take paracetamol, but it is advised not to take ibuprofen because there is a risk of a serious skin condition.

If your child is dehydrated, simple medications are not reducing their fever, there are signs that their spots may be infected (red, hot and painful) or you are worried about your child in any sense, it's best to speak to your doctor for advice.

What about the chickenpox vaccine?

You can get the chickenpox vaccine on the NHS if there's a risk of harming someone with a weakened immune system if you spread the virus to them (for example, a child can be vaccinated if one of their parents is having chemotherapy treatment for cancer). You can also pay to have the vaccine at some private clinics or travel clinics.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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