Chickenpox

Published by Bupa’s Health Information Team, December 2011.

This factsheet is for people who have chickenpox, or who would like information about it including the symptoms, causes and treatments.

Chickenpox is a highly contagious infection. It causes an itchy rash, consisting of small, raised, blistered or crusted spots.

About chickenpox

Chickenpox is a common infection caused by the varicella zoster virus. It’s most commonly seen in children under 10, but you can catch it at any age. Once you have had chickenpox, you’re very unlikely to catch it again.

For most people, chickenpox usually goes away after a week or so. Once your symptoms have cleared up, the virus stays dormant in your body for the rest of your life. At any time later in life, the virus can be reactivated. This causes shingles, which is a related disease caused by the same varicella zoster virus.

You can catch chickenpox at any time throughout the year, but it’s most common in winter and spring.

There is a very small chance that you can get chickenpox more than once, especially if you have a weakened immune system (for example, you have HIV/AIDS or are taking medicines that suppress the immune system).

Symptoms of chickenpox

You will begin to get symptoms 11 to 21 days after infection. Initial symptoms of chickenpox include: 

• mild headache
• fever
• loss of appetite
• coughing or sneezing
• a general feeling of being unwell

A day or two after the first symptoms begin, you will develop a small, flat rash with red spots. The fluid-filled spots are usually very itchy and vary in size. You will usually get spots on your face and scalp first, which may then spread to your chest, arms and legs. You may also get spots inside your mouth and nose. 

Chickenpox

Your spots can develop into pustules (blisters containing pus). The blisters will usually crust over within a few days to form scabs and the spots usually take around two weeks to heal completely. They don’t usually leave a scar, unless they get infected. This can happen if you scratch them.

Chickenpox blisters

The severity of chickenpox infection varies – it’s possible for children to be infected but show no symptoms. Chickenpox is more severe in adults.

These symptoms aren’t always caused by chickenpox but if you have them, see your GP.

Complications of chickenpox

In otherwise healthy people, chickenpox is usually a mild infection and serious problems are rare. Chickenpox can be more serious for adults, babies or people who have a weakened immune system, such as those who have HIV/AIDS, or those who are taking medicines that suppress the immune system.

Occasionally, healthy people get other problems from having chickenpox. For example, your rash or spots could become infected. This may delay the healing process and can leave you with scars.

The most frequent and dangerous complication of chickenpox is pneumonitis (inflammation of your lung tissue). You’re more likely to get this if you smoke.

Sometimes, although it’s rare, chickenpox can cause encephalitis (inflammation of your brain) or pneumonia (an infection in your lungs). Some children and adults may develop ataxia, which causes unsteadiness and loss of co-ordination. This usually develops between a week and 10 days after you become infected with chickenpox. The ataxia usually begins to improve within a few weeks but may persist for as long as two months. Most people will recover without any treatment.

At any time later in life, the varicella zoster virus can be reactivated. If this happens, you will develop shingles. Shingles causes a blistering rash that usually appears on one side of your body. It can be very painful. You can’t develop shingles from exposure to a person with chickenpox, but you can develop chickenpox as a result of exposure to someone with shingles if you haven’t had it before.

Causes of chickenpox

Chickenpox is highly contagious. If you come into contact with someone who has chickenpox and you haven’t previously had it, you have a very high chance of catching it.

Chickenpox is transferred through direct person-to-person contact, usually through the air when you cough or sneeze. You can also catch the virus through contact with infected clothing or bedding.

The incubation period (the time from when you become infected to when your symptoms first appear) is between 11 and 21 days. The most infectious period is one to two days before the rash appears, but you can still catch it from someone until all the spots have crusted over. This is usually about five to six days after the onset of the chickenpox rash. See our common questions for more information.

Diagnosis of chickenpox

In most cases, you can diagnose chickenpox from its characteristic rash. If you have recently been in contact with anyone who has chickenpox this can help to confirm your diagnosis. If you have any doubt, or if you're pregnant or have a weakened immune system, see your GP for advice.

Treatment of chickenpox

There is no specific treatment for chickenpox and you will usually get better without any medicine.

Self-help

You can take the following simple measures to help reduce your symptoms.

• Drink enough fluids.
• Dress appropriately so that you’re not too hot or cold.
• Wear smooth, cotton fabrics to reduce any irritation to your rash.
• Keep your nails short to reduce any skin damage caused by scratching.

Medicines

Chickenpox spots are usually very itchy, but try not to scratch them. Eurax cream may help soothe and reduce the itchiness of your rash. You can buy this at a pharmacy. You can give your child paracetamol syrup (eg Calpol) to reduce fever and pain. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.

A stronger medicine, called chlorphenamine, can be prescribed by your GP to relieve itching. It's taken by mouth and is suitable for children over the age of one. Some people may take antihistamines, but there is very limited evidence to suggest that these help reduce itchiness.

If you develop serious complications of chickenpox, particularly pneumonitis or encephalitis, you may be given antiviral medicines to try to get rid of the virus more quickly. Aciclovir (Zovirax) is a medicine that helps you fight the varicella zoster virus. If you take it within a day of getting ill, your chickenpox will probably be milder. As a side-effect, aciclovir can sometimes cause diarrhoea and make you feel sick.

You may also be offered an injection that contains antibodies (proteins produced by the immune system that usually fight against bacteria and viruses) to help fight your chickenpox. However, you need to have this within 10 days of coming into contact with someone who has chickenpox for it to work.

Prevention of chickenpox

If you have chickenpox, try to stay away from people who haven’t had it, especially pregnant women, newborn babies and those with a weakened immune system.

Keep your child off school or nursery for five days from the onset of the rash or until all the spots have crusted over. Air travel isn’t allowed until six days after the last spot has appeared.

There is a vaccine that can help prevent chickenpox, but it’s only recommended for certain people, such as healthcare workers and for those in contact with someone with a weakened immune system. See our common questions for more information. If you're thinking about getting pregnant, ask your GP about the vaccine, because catching chickenpox during your pregnancy could harm your unborn baby.

Special considerations

If you’re pregnant

If you're pregnant and come into contact with someone who has chickenpox, there is no problem if you have had chickenpox before or have been vaccinated. If you have never had chickenpox, or aren’t sure, see your GP as soon as possible. You can have a blood test to find out if you’re immune. If you develop any rash during pregnancy, always contact your GP or midwife.

Chickenpox in the first half of pregnancy

If you aren’t immune to chickenpox and you come into contact with someone who has it during the first six months of pregnancy, there is a small risk it could affect your baby. You may be given an injection of varicella zoster immune globulin. This is a human blood product that strengthens the immune system for a short time. It doesn’t always prevent you from developing chickenpox but it can mean your symptoms are milder and don’t last as long if you do catch it.

You can have the injection up to 10 days after you come into contact with chickenpox and before any of your symptoms appear. Varicella zoster immune globulin doesn’t work once your spots have developed into blisters.

Chickenpox in the second half of pregnancy

If you get chickenpox in the second half of your pregnancy, you may be given aciclovir. If you get chickenpox late in your pregnancy, especially around the time you give birth, your baby could develop chickenpox. See your GP if you get chickenpox within a week of giving birth. You and your baby can be treated with aciclovir or injections of antibodies.

It’s safe to breastfeed if you have or have had chickenpox during pregnancy. When your baby is seven months old, a blood test can check if he or she has antibodies to chickenpox. If you baby has these antibodies, it means that he or she has developed an immunity to the virus and won’t catch it again.

If you catch chickenpox during pregnancy or when you’re trying to become pregnant, you should stay away from other pregnant women and newborn babies until all your blisters have crusted over.

If you have a weakened immune system

If you have a weakened immune system or you’re older than 65, you’re more likely to have serious complications as a result of catching chickenpox. If you come into contact with someone who has chickenpox and you haven’t had it before, see your GP straight away. The best way to prevent infection is to make sure that people you live with have the chickenpox vaccine.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.