Chickenpox is a contagious disease caused by the varicella-zoster virus (VZV) which is also responsible for shingles (herpes zoster). Chickenpox manifests as a skin rash which forms small, itchy blisters. It can also come with symptoms such as fever, fatigue and headaches, and typically lasts between 5-7 days. It has a very high transmission rate, and is transmitted through airborne VZV particles. Following exposure to the virus, most people are immune for life; most people get it before the age of 10, therefore 95% of adults are immune to chickenpox. The disease is usually more severe in adults than it is in children.¹

Chickenpox in adults

Chickenpox in adults can be severe, particularly in people who are pregnant or otherwise immunocompromised. This may be because adults have a stronger immune system than children, so the immune response is more vigorous which results in more severe symptoms or complications. 

The symptoms of chickenpox in adults are very similar to those in children:

• Fever
• Fatigue
• Headache
• Stomach ache
• Blistering skin rash

Chickenpox in adults can lead to various complications such as cellulitis, pneumonia, meningitis and encephalitis. These severe complications become more common with age, and were observed more often in immunocompromised patients. It’s thought that some of these infections can occur when chickenpox blisters open, providing an entrance for bacteria and virus particles to enter the body.²

Home care and symptom management

The NHS recommends the following for taking care of chickenpox at home:

• Drink plenty of fluids to avoid becoming dehydrated
• Take paracetamol to help with pain
• Use calamine lotion to help with itching
• Keep the skin moisturised to prevent itchiness and dryness
• Bathe in cool water and pat the skin dry
• Wear loose clothes

Avoid scratching spots, as this can open them, leading to increased risk of additional bacterial or viral infections.

Pharmaceutical treatments for chickenpox in adults

Acyclovir is an antiviral drug, usually used as a treatment for herpes simplex virus (HSV). However, it can also be taken in tablet form to treat chickenpox. It stops viruses from replicating by incorporating itself into viral DNA, and is most effective if taken within 24-48 hours of rash onset. For immunocompromised patients, it is often recommended that an intravenous version of acyclovir is given as it is a faster method of drug administration. There is no evidence to suggest that taking acyclovir while pregnant is unsafe, however, the manufacturer recommends that pregnant people still take caution and seek advice from their doctor before taking it.³

Other medications may be prescribed by a doctor to treat any secondary infections.

The chickenpox vaccine

A vaccine for chickenpox was created in the 1990s, but is not available as a routine childhood vaccine in the UK due to concerns about its cost-effectiveness and the risk that it would actually increase varicella zoster and herpes zoster cases in adult populations. Therefore, it has mostly only been available privately or for those who work in the healthcare sector or share a household with somebody who is immunocompromised.⁵

However, following the success of the vaccine in other countries, in 2023 the Joint Committee on Vaccination and Immunisation (JCVI) recommended that the vaccine be added to the UK’s routine childhood immunisation programme. It is currently awaiting approval.

Preventing the spread of chickenpox

Since chickenpox is spread through the air, it is advised to avoid being in the same room as somebody who has the disease. Some evidence suggests that the virus is not contagious until spots are present, while others say that the virus can be spread from nasal discharge 1-2 days before physical symptoms are present.⁴ This is why it is important to maintain regular disease prevention methods, such as covering the nose and mouth when coughing or sneezing, frequently washing hands and keeping regularly touched surfaces clean.

Risk of shingles

Adults who are immune against chickenpox are at risk of contracting shingles. Shingles is caused by the herpes zoster virus, which is a result of the reactivation of varicella zoster. 

The transmission of shingles is very similar to that of chickenpox, but the physical symptoms vary slightly. The rash usually collects in one area of the body, rather than being spread out. The skin affected by the rash will be painful and potentially feel tingly. Other symptoms such as headache, fever and fatigue may also be experienced. In 50% of shingles cases, ocular (eye) diseases may also occur, such as: conjunctivitis or uveitis.

When to seek medical attention

The NHS recommends that you seek medical attention if:

• The skin surrounding chickenpox blisters is hot, painful and red
• You’re pregnant or immunocompromised and have been in contact with someone who has chickenpox, and you haven’t had it before
• You have a fever above 38.9℃
• You’re experiencing frequent vomiting
• You’re having difficulty breathing

Summary

Chickenpox is a contagious disease caused by the varicella-zoster virus (VCV). It is characterised by small, itchy blisters or spots which cover the skin. The rash usually lasts between 5-7 days and goes away by itself, however, it can be a lot more serious in adults than in children, leading to serious complications such as pneumonia and meningitis. Treatments for chickenpox in adult patients include using calamine lotion to help with itching. The antiviral drug acyclovir has also been shown to be effective in treating chickenpox if taken 24-48 hours after physical symptoms present themselves. A vaccine against chickenpox was recommended by the JCVI in 2023 to be added to the UK’s routine childhood immunisation programme and is currently waiting to be approved.