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Published by Bupa's health information team, January 2010.
This factsheet is for people who have chickenpox, or who would like information about it.
Chickenpox is a common illness caused by a virus. It gives you a rash and can make you feel generally unwell.
Chickenpox is an infection caused by the varicella zoster virus, which is part of the herpes group of viruses.
Anyone can catch chickenpox, but it mainly affects children under 10. Most people will have had chickenpox by the age of 15.
Once your symptoms have cleared up, the virus stays dormant in your body. At any time later in life, usually in adulthood, the virus can re-activate, causing shingles.
Symptoms of chickenpox
You will start to get symptoms around 10 to 21 days after you catch the virus.
The first symptoms of chickenpox include:
- sore throat
- feeling generally unwell
You may have these symptoms for a few days before you get any spots. Chickenpox spots are usually very itchy. They vary in size and appear in clusters on your skin, forming a rash. You will usually get spots on your face and scalp first, then they may spread to your chest, arms and legs. You may also get spots inside your mouth and nose.
The spots are fluid-filled blisters surrounded by reddened skin. They may develop into pustules (blisters containing pus). The blisters or pustules will then crust over to form scabs. The spots usually take around 16 days to heal completely.
Chickenpox is usually worse in adults than children. Adults are more likely to have complications as a result of chickenpox and are more likely to be left with rounded, hollowed-out scars on the skin, known as 'pockmarks'.
Complications of chickenpox
In otherwise healthy people, chickenpox is usually a mild infection and serious problems are rare.
The most common problem linked with chickenpox in children is a bacterial infection in the spots. This causes the surrounding skin to become more red and sore. Your child's GP may prescribe antibiotics to treat the infection. Some children may also develop a middle ear infection.
Rarely, chickenpox can cause encephalitis (inflammation of your brain) or pneumonia (an infection of your lungs). Varicella pneumonia is the most common complication in adults and causes wheezing and rapid breathing three to four days after the rash appears for the first time.
Up to eight days after the chickenpox rash develops, some children and adults may become clumsy and unable to walk properly. This is called ataxia. It's caused by inflammation in a part of your brain called the cerebellum. This usually settles down on its own, but occasionally other parts of your brain become affected and it can cause longer-term problems.
Causes of chickenpox
Chickenpox is caused by the varicella zoster virus and is very contagious. If you haven't had chickenpox before and someone you live with has it, you have a very high chance of catching it.
The virus is usually transferred from person to person through the air in the fine spray of saliva or mucous droplets when you cough or sneeze. It can also be passed from person to person through contact with the fluid from chickenpox blisters, either from a person who is infected or by items such as clothing that have been in contact with broken blisters.
If you have chickenpox, you can pass the virus on about one to two days before the rash breaks out. You remain infectious until your spots have crusted over, usually five to six days after the illness starts. Children should be kept home from school or nursery during this time.
Once you have had chickenpox, you will usually be immune and won't catch it again. However, on rare occasions people can get it again.
It's also possible to get chickenpox from someone who has shingles, through contact with fluid from the shingles rash. However, it's not possible to catch shingles from someone who has chickenpox.
Treatment of chickenpox
Most people with chickenpox get better without any treatment. However, over-the-counter treatments are available to help relieve your symptoms.
It can be difficult to resist, but try not to scratch your spots as this can lead to scarring. Keep children's nails short to minimise the damage from scratching.
You can help relieve the itchiness by keeping your skin cool - wear light clothing and bathe or sponge your skin with tepid water. This will also help to reduce a high temperature. Adding half to one cup of bicarbonate of soda to a warm bath can be soothing.
You may find crotamiton cream or lotion helps to soothe itching. You can buy this from your pharmacist. It's suitable for children over three years. Calamine lotion, which is the traditional alternative, isn't as effective.
Some people take antihistamine tablets to help reduce the itchiness, but there is little evidence to suggest that this helps. Some antihistamines can make you very drowsy, so may help you sleep and therefore stop you scratching at night. The sedating antihistamine chlorphenamine is suitable for itching in chickenpox for children over one year.
Over-the-counter painkillers, such as paracetamol and ibruprofen, may ease your discomfort if your skin is painful, and will help lower a fever and relieve a sore throat. Always read the patient information leaflet that comes with the medicine and, if you have any questions, ask your pharmacist for advice.
Prevention of chickenpox
If you have chickenpox, try to stay away from public areas to avoid contact with people who haven't had it, especially newborn babies, pregnant women and people with a weakened immune system.
To prevent chickenpox spreading, children should be kept off school until all of the spots have crusted over.
There is a vaccine for chickenpox, but it's currently only given to certain people, such as healthcare workers who have direct contact with patients and haven't had chickenpox or shingles before. This is to protect patients from catching chickenpox from an infected carer. The vaccine is given in two doses four to eight weeks apart.
If you're pregnant
Most women of childbearing age will have had chickenpox and will be immune. However, if you haven't had chickenpox before and catch it when you're pregnant it can make you feel very unwell and some women can develop pneumonia.
Depending on how many weeks pregnant you are, chickenpox may affect your unborn baby.
Chickenpox in the first half of pregnancy
If you catch chickenpox in the first 20 weeks of pregnancy, it may, in rare cases, affect your unborn baby. It can affect the development of your baby's arms, legs, brain or eyes, and cause scarring on his or her skin and poor growth. This is called fetal varicella syndrome.
Chickenpox in the second half of pregnancy
If you get chickenpox after 28 weeks of pregnancy there doesn't seem to be any risk of it causing your baby to develop an abnormality. However, your baby may catch it from you and develop a type of chickenpox called symptomatic varicella infection. This means your baby may be ill when he or she is born. Your baby's infection may be worse if you develop chickenpox within five days before delivery and up to two days after.
Contact your GP as soon as possible if you're pregnant and think you have chickenpox or if you develop symptoms within seven days of giving birth.
Treatment for pregnant women
If you're more than 20 weeks pregnant and get chickenpox, your doctor may prescribe an antiviral medicine called aciclovir. Although this doesn't cure the illness, it makes it less severe. You need to start taking this medicine within 24 hours of the rash appearing. Aciclovir is sometimes also prescribed for newborn babies.
If you have been in contact with someone who has chickenpox and you haven't already had it yourself, contact your GP as soon as possible. You can have an injection called varicella zoster immunoglobulin (VZIG), which contains antibodies against the virus. This will stop you getting chickenpox, but you need to have the injection within 10 days of exposure to the virus.
If you have a weakened immune system
You're more at risk of severe complications from chickenpox if you have a weakened immune system, for example if you're having treatment for cancer, you have HIV/AIDS or you're over 65. Contact your GP as soon as possible if you have come into contact with someone who has chickenpox and you haven't had it before. Your GP can then prescribe the appropriate treatment.
See our answers to common questions about chickenpox, including:
- Chickenpox: background information. Clinical Knowledge Summaries. www.cks.nhs.uk, accessed 22 September 2009
- Allen S. Chickenpox and shingles infection. Pharm 2006; 277:453-56. www.pharmj.com
- General information - chickenpox (varicella). Health Protection Agency. www.hpa.org.uk, accessed 22 September 2009
- Chickenpox encephalitis. GP Notebook. www.gpnotebook.co.uk, accessed 22 September 2009
- Further information about varicella (chickenpox) vaccine for health professionals. NHS Immunisation Information. www.immunisation.nhs.uk, accessed 22 September 2009
- Chickenpox in pregnancy. Royal College of Obstetricians and Gynaecologists. www.rcog.org.uk, accessed 22 September 2009
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: January 2010