Chickenpox
Symptoms, Causes & Treatment
Understanding chickenpox: what to expect, who needs antiviral treatment, and how to prevent complications in children and adults.
What Is Chickenpox?
Chickenpox (varicella) is a highly contagious viral infection caused by the varicella-zoster virus (VZV). It produces a characteristic itchy, blistering rash along with fever and general malaise. Chickenpox is most common in children, with the majority of cases occurring before the age of 10, though it can affect people of any age.
In healthy children, chickenpox is usually a mild, self-limiting illness that resolves within 1–2 weeks. However, chickenpox can be more severe and potentially dangerous in certain groups: newborns, adults (particularly those who did not have chickenpox in childhood), pregnant women, and immunosuppressed individuals.
Chickenpox is caused by the same virus as shingles. After the initial infection resolves, VZV remains dormant in the nerve ganglia and can reactivate later in life as shingles (herpes zoster).
In the UK, chickenpox vaccination is not part of the routine childhood immunisation programme (unlike many other countries), though it is available privately and is offered to certain at-risk groups through the NHS.
What Are the Symptoms of Chickenpox?
Chickenpox has a characteristic progression of rash stages. Multiple stages are present simultaneously, which is diagnostic.
Generalised, intensely itchy blister rash developing in crops · Red spots that become fluid-filled blisters then crust over · Mild fever, fatigue, headache · Rash appears first on trunk, spreading to face and limbs · Lesions in different stages simultaneously · Infectious 2 days before rash until all blisters crusted
Chickenpox in adults (more severe than childhood) · Chickenpox in pregnancy (risk of congenital varicella syndrome) · Chickenpox with breathlessness (varicella pneumonia) · Signs of bacterial superinfection (cellulitis, high fever) · Chickenpox in immunocompromised individuals (antiviral treatment urgent)
Seek urgent assessment if a person with chickenpox develops difficulty breathing, severe headache, confusion, very red inflamed skin, or if the person is pregnant, immunocompromised, a newborn, or an adult with severe symptoms.
What Causes Chickenpox?
Chickenpox is caused by primary infection with the varicella-zoster virus (VZV), which spreads through respiratory droplets and direct contact with vesicle fluid.
Varicella zoster virus (VZV) is transmitted via respiratory droplets and direct contact with vesicle fluid. Primary infection in non-immune individuals causes chickenpox. Immunity is usually lifelong after infection.
Contact dermatitis occurs when skin comes into contact with an irritant (irritant contact dermatitis) or a specific allergen (allergic contact dermatitis via type IV delayed hypersensitivity). Common allergens: nickel, latex, fragrances, preservatives.
Common eczema triggers include wool, synthetic fabrics, dust mites, pet dander, pollen, mould, soaps, detergents, food allergens (in children), and emotional stress. Identifying and avoiding personal triggers reduces flare frequency.
Psoriasis is an immune-mediated chronic inflammatory skin disease. T-cell activation drives rapid keratinocyte proliferation (3–5 days instead of 28–30), producing the characteristic thickened plaques.
Multiple psoriasis triggers are recognised: streptococcal throat infection (especially guttate psoriasis), medications (lithium, beta-blockers, antimalarials, NSAIDs), stress, trauma (Koebner phenomenon), alcohol, and smoking.
Around 30% of people with skin psoriasis develop psoriatic arthritis — an inflammatory arthropathy with joint erosions, enthesitis, and dactylitis. It can be severe and requires DMARD treatment to prevent joint destruction.
Key Risk Factors
How Is Chickenpox Diagnosed?
Chickenpox is diagnosed clinically on the characteristic itchy, vesicular rash in different stages simultaneously. VZV PCR from vesicle fluid confirms diagnosis in atypical or severe cases. Varicella IgG confirms immunity in contacts.
How Is Chickenpox Treated?
Management is based on patient risk group. Healthy children need only supportive care. Antiviral treatment is required for at-risk groups.
Supportive Measures
Calamine lotion or cooling gel relieves itch. Trim fingernails and use cotton mittens in children to prevent scratching and scarring. Paracetamol for fever and pain (NOT aspirin or ibuprofen in children). Oatmeal baths soothe the skin. Keep cool to reduce itch.
After Chickenpox: Preventing Shingles
After chickenpox, VZV lies dormant in dorsal root ganglia and can reactivate decades later as shingles. The Shingrix vaccine is recommended for adults 70–79 on the NHS. Children who have had chickenpox do not need vaccination.
When Should You Seek Medical Advice for Chickenpox?
Chickenpox with difficulty breathing (pneumonia) · Severe headache, photophobia, or stiff neck (meningitis) · Rash becoming very red, warm, and swollen (bacterial superinfection) · Newborn or immunocompromised patient with chickenpox.
An adult household member has developed chickenpox · You are pregnant and exposed to chickenpox · A child has chickenpox and is becoming increasingly unwell · The rash is becoming very inflamed or infected.
How Can You Prevent Chickenpox?
Chickenpox can be prevented through vaccination. Infection control measures reduce spread.
Chickenpox spreads by airborne droplets and direct contact. Keep infected children at home until all blisters have crusted (typically 5 days from rash onset). Inform school and close contacts, especially pregnant women and immunocompromised individuals.
Varivax and Varilrix chickenpox vaccines are not on the routine UK schedule but are offered to non-immune healthcare workers and household contacts of immunocompromised patients. Consider vaccination for seronegative adults planning pregnancy.
Frequent, effective milk removal is the most important mastitis prevention. Feed or express every 2–3 hours; never skip feeds. Get breastfeeding support from a midwife, health visitor, or lactation consultant early — before problems develop.
Ensure your baby latches on deeply and correctly. A poor latch causes nipple trauma (cracks), which are an entry point for bacteria. Ask for a latch assessment if breastfeeding is painful.
Seek breastfeeding support immediately if you notice breast hardness, redness, or pain. Early identification and treatment of blocked ducts prevents progression to mastitis and abscess.
SPF 30+ sunscreen daily is the single most effective measure against all types of hyperpigmentation, including melasma, PIH, and solar lentigines. UV exposure stimulates melanin even on cloudy days. Apply year-round to face and neck.
Speak to a Clinician About Chickenpox
Through The GP Service, a licensed clinician can assess chickenpox, prescribe antivirals for at-risk groups, and advise on management and isolation.
Expert clinical advice, when you need it.
Chickenpox FAQs
Chickenpox is caused by the varicella-zoster virus and spreads through respiratory droplets and contact with blister fluid. It is highly contagious from 1–2 days before the rash appears until all blisters have crusted over (usually 5–7 days after onset).
Most healthy children recover fully without complications. Serious complications — including bacterial skin infections, pneumonia, and encephalitis — are rare in healthy children but more common in adults, pregnant women, newborns, and immunocompromised individuals.
Seek urgent medical advice if anyone with chickenpox develops difficulty breathing, severe headache, confusion, a rash that becomes very red, warm, or tender (suggesting secondary infection), or if the person is pregnant, immunocompromised, or a newborn.
Antiviral treatment (aciclovir or valaciclovir) is recommended for adults with chickenpox, pregnant women, immunocompromised individuals, and newborns. It is not routinely required for healthy children where symptoms are mild.
Children should stay off school until all blisters have crusted over. This is typically 5 days after the rash first appears. They can return when all spots are dry and crusted, even if some crusts remain.
The chickenpox (varicella) vaccine is available privately in the UK and is highly effective. It is not routinely offered on the NHS schedule but is available as a private vaccination. Two doses are required for best protection.
After chickenpox, the varicella-zoster virus remains dormant in nerve tissue. Decades later, particularly when immunity is reduced by age or illness, it can reactivate as shingles — a painful unilateral rash in a nerve distribution.
Pregnant women who have not had chickenpox and are exposed should contact their GP or midwife urgently. Varicella can cause serious complications in pregnancy. Varicella-zoster immunoglobulin (VZIG) can be given to reduce severity if administered promptly.