Everything you need to know about chickenpox

Chickenpox is a highly contagious, itchy rash caused by the varicella zoster virus. In the UK, most children will catch chickenpox at some point in their childhood and this will usually give them lifelong immunity against the condition, making it highly unlikely that they will develop chickenpox again. Consequently, around 90% of adults who have grown up in the UK have immunity against chickenpox. However, for those individuals who do catch chickenpox in adulthood, the symptoms are usually more severe than in children. 

Symptoms of chickenpox

Chickenpox can develop anywhere on your body, including in your mouth, eyelids and genitals. However, the spotty rash usually first appears on your back, chest and face before spreading elsewhere.

Before the spots appear, you may develop a fever and feel achy, unwell and/or tired. Adults who develop chickenpox usually have a fever for longer and develop more spots than children.

It usually takes one to three weeks after infection with the virus for the spots to appear. The spots follow three stages of development; you may have spots at different stages on your body at the same time.

Stages of chickenpox 

The three stages of chickenpox refer to how the spots on your body change over time. 

During stage one, small spots appear on part of your body, most often the back, chest or face. On light skin, these spots appear red or pink. On dark skin, these spots may appear the same colour as your skin or darker and may be harder to see. At this stage, the spots may stay in the same area or spread. 

During stage two, the spots fill with water, forming itchy blisters that may burst. 

During stage three, the blisters scab over and may continue to leak or become flakey. 

How is chickenpox spread?

Chickenpox spreads through contact with droplets containing the virus from coughing or sneezing, or contact with leaking blisters, mucus or saliva of someone who is infected.

This means that if you have chickenpox, you are usually contagious from two days before your spots appear until the last of these spots scab over, which usually takes about five days from the time a spot first develops.

Complications of chickenpox

Complications in children

Although chickenpox is unpleasant, in otherwise healthy children, it very rarely causes complications.

The most common complication is an infection of the blisters with bacteria, causing the surrounding skin to become red and sore. In some cases, a course of antibiotics is needed to treat the infection.

Very rare complications of chickenpox in children occur when the virus infects the whole brain (encephalitis), part of the brain called the cerebellum (cerebellitis) or the linings of the brain (meningitis). Symptoms of these rare complications include changes in behaviour, difficulty walking, balancing or talking, as well as:

• A stiff neck
• Confusion and/or dizziness
• Drowsiness and/or fatigue
• Seizures 
• Severe headaches
• Vomiting

Another very rare complication of chickenpox is pneumonia, where the virus spreads to the lungs and causes inflammation. Symptoms of pneumonia include abdominal and/or chest pain, fatigue, a cough, laboured breathing (you will see the muscles under your child's ribcage pull inwards when they inhale), loss of appetite and vomiting. 

If you notice any of the above symptoms in your child, seek immediate medical attention.

Complications in adults

Although complications of chickenpox are more common in adults, most adults who are otherwise healthy still recover without developing serious complications.

Adults can develop the same complications as children with chickenpox ie infection of the blisters with bacteria, cerebellitis, encephalitis, meningitis and pneumonia — around 5–14% of adults with chickenpox will develop pneumonia.

Who is most at risk of complications?

Children and adults who are otherwise healthy are unlikely to develop complications from chickenpox. However, the very old and very young (babies aged four weeks or less) are at increased risk, as well as pregnant women or anyone with a weakened immune system eg if you’re taking long-term steroids or undergoing chemotherapy, have cancer or HIV, or have had an organ transplant.

Pregnancy and chickenpox

If you’re pregnant and haven’t had chickenpox before but think you’ve been exposed, contact your GP as soon as possible. They may recommend an injection that contains antibodies against the chickenpox virus. When given within 10 days of exposure, this injection can reduce the risk of developing chickenpox or reduce its severity.

If you’re pregnant and develop symptoms of chickenpox, see your GP immediately. They may recommend an antiviral medication to speed up your recovery. The medication is most effective when taken within 24 hours of your rash developing.

Risks to your unborn baby

If you develop chickenpox while pregnant, there is a very small chance your baby may develop foetal varicella syndrome (FVS), which refers to a group of serious birth defects. After week 20 of pregnancy, the risk of your baby developing FVS is incredibly small, with no known cases in the UK after week 28.

If you develop chickenpox at the end of your pregnancy or within a week after delivery, your baby may have been exposed to the virus that causes chickenpox. Your care team will recommend vaccinating your baby to prevent them from developing neonatal chickenpox.

When should you see a doctor?

For most healthy adults and children, chickenpox will get better without needing to see a doctor. However, if you’re pregnant or have a weakened immune system, see your GP as soon as you develop symptoms. If your baby is aged four weeks or under and develops chickenpox, you should also take them to see your GP.

If you or your child has chickenpox but is otherwise healthy, you only need to see your GP if: 

• You’re concerned about the symptoms
• You notice that the skin around the blisters becomes warm or red — this may indicate an infection
• Your or your child’s rash spreads to the eyes
• You notice symptoms of complications — this includes: 
• A stiff neck
• Confusion, dizziness, drowsiness and/or fatigue
• Difficulty balancing, talking or walking
• Laboured breathing
• Seizures 
• Severe headaches and/or vomiting

Treating chickenpox at home

In most cases, chickenpox can be treated at home. It is important that you do not go to work, school or socialise until you are no longer contagious ie all of your blisters have scabbed over and stopped leaking.

While you’re recovering, make sure you drink lots of water, wear loose clothing, take cool baths or showers and pat your skin dry rather than rubbing it. You should also avoid scratching your spots — in young children, you may want to put socks on their hands when they're sleeping to help.

You can take paracetamol to soothe any discomfort but do not take any non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, as this can lead to complications, including a dangerous skin infection called necrotising fasciitis.

To provide temporary relief from itchy spots, speak to a pharmacist about taking an antihistamine medication and/or try applying over-the-counter cooling gels or creams.

You should recover within one to two weeks of your symptoms starting.

Chickenpox and shingles

Shingles is caused by the same virus that causes chickenpox — varicella zoster. After you’ve had chickenpox, a small amount of the virus stays in your body but is dormant ie not active and not causing any symptoms.

However, if your immune system is weakened at any point in the future, the virus can become active again. This doesn’t cause chickenpox but instead causes shingles. You, therefore, can’t catch shingles from exposure to chickenpox.

Around one in four people in the UK will develop shingles in their lifetime. The main symptoms are pain and itchy blisters, which usually last for two to four weeks. Unlike chickenpox, shingles doesn’t spread across your whole body but instead is limited to one side of your body, often one specific area.

In most cases, shingles will get better on its own. However, if you have a weakened immune system, are under 18 or are pregnant, you should see your GP.

To avoid spreading the virus to someone who has not yet had chickenpox, keep your blisters covered and avoid contact with children, pregnant women and anyone with a weakened immune system.