What is chickenpox?

Chickenpox (also known as varicella) is an infectious disease caused by the varicella-zoster virus. Reactivation of the dormant virus after a bout of chickenpox leads to herpes zoster (shingles).

Most chickenpox infections are mild to moderate and self-limiting. It is highly infectious in children.1 Approximately 90% of people get infected when they come into contact with someone who has chickenpox.

Nearly all children in the UK will catch chickenpox by the age of 10.2 The vaccination is available on the NHS for groups who are at high risk.

The following is a summary about the disease. For further details speak to your local pharmacist or GP.

How is chickenpox spread?

Chickenpox is highly infectious and spread throughout households is very common. Chickenpox can spread easily to people who have not had it before.

The chickenpox virus is spread through the air via droplets when coughing or sneezing or by contact with infected surfaces or blisters.1

Who is at risk of chickenpox?

The infection is most common in children below the age of 10, in whom it usually causes mild disease.

The disease can be more serious in:

  • Adults
  • Pregnant women (greater risk during later stage of the second trimester and early stage in third trimester)

Smokers (greater risk of varicella pneumonia)3

What are the signs and symptons of chickenpox?

The incubation period between exposure and the first skin lesions can be between 10-21 days.

Symptoms include:

  • Fever for up to 4 days
  • Headaches
  • Stomach ache
  • General feeling of being unwell
  • Blisters appear over the course of 3-5 days

The spots initially start of as small pimple-like rash and turn red and itchy.

They develop into fluid filled blisters. These blisters mostly occur on the head, neck and trunk, and sparsely on the arms and legs. They can also occasionally occur in the mouth. The blisters tend to be very itchy.

The blisters start drying out form crusts. When this falls off they may leave marks for a few week but there is usually no long term scarring; however, in adolescents and adults there is a greater risk of scarring.

Chicken pox is infectious from 2 days before the spots appear until they have crusted over. It is important to avoid scratching these spots as they may be susceptible to bacterial infection.1

What are the complications of chickenpox?

In people who are immunocompromised the following may also occur:

  • Spots may continue over several weeks
  • Blisters may be large and start to bleed
  • Pneumonia is more common5

What is the treatment for chickenpox?

Chickenpox is usually self-limiting and treatment is symptomatic:

  • Maintain adequate fluid intake
  • Antihistamines to relieve itching
  • Emollient creams (such as calamine lotion and aqueous calamine cream) to help soothe itching
  • Paracetamol for fever and aches


  • Anti-inflammatory medications such as Ibuprofen
  • Scratching spots as this can lead to bacterial infection1
  • Avoid school/nursery for 5 days after the first spots appeared4

Secondary infection may require antibiotics.1

What advice is there for travellers?

If flying with chicken pox, it is recommended to contact air lines as their policies regarding travel vary from 6 days of appearance of last blister or until all spots are dried and crusted. Some airlines may require a letter from the GP stating the spots are no longer contagious.

When to consider vaccination?

Chickenpox vaccination is offered on the NHS to people who are in close contact with someone who is particularly vulnerable to chickenpox or its complications. However it is also available privately through certain pharmacies and travel clinics.

People with a weakened immune system include:

  • Taking long-term steroid tablets
  • Undergoing  chemotherapy treatment
  • Who have had their spleen removed
  • Who have had an organ transplant and are using immunosuppressant medicines
  • Diagnosed with HIV or AIDS

It is recommended for:

  •  Non-immune healthcare workers (including non-medical staff working in hospitals and GP surgeries)
  •  Siblings of a child who has leukaemia
  • Children whose parents are undergoing chemotherapy4

Some travel clinics and certain pharmacies offer private chickenpox vaccinations for children and adults.


The chickenpox vaccine is a live vaccine and contains a small amount of weakened chickenpox-causing virus. The vaccine stimulates the immune system to produce antibodies that will help protect against chickenpox.

The vaccination is suitable for adults and children over the age of 1.

The vaccine is usually given as 2 separate injections, 4 to 8 weeks apart.6 Two doses of the vaccination give 98% protection to children and 75% protection in teenagers and adults.7


This information is taken from trusted third party websites, NaTHNaC (Travel Health Pro) and EMIS (Patient info) and use of all information has been licenced under the Open Government Licence

Although the materials are being used/replicated under the provisions of the Open Government Licence this in no way represents endorsement of by NaTHNaC, Emis, Public Health England, the NHS or the Department of Health and Social Care.


  1. Chickenpox
  2. Vaccine Knowledge Project: Chickenpox (varicella)
  3. The Green Book: Varicella Chapter 34
  4. NHS: Chickenpox
  5. Chickenpox
  6. NHS: Chickenpox vaccination
  7. Vaccine Knowledge Project: Chickenpox (varicella) vaccine