Chickenpox is an infection caused by the varicella-zoster virus. It is best known for its itchy rash, but early symptoms can begin before spots appear. The illness is often mild in children, although it can be more serious in adults, newborns, pregnant people and people with weakened immune systems.

This guide explains common signs of chickenpox, how the rash typically develops, when a person may be contagious and when to seek medical advice. Symptoms can vary, and a rash cannot be diagnosed reliably from written information alone.

What does chickenpox usually look and feel like?

Typical chickenpox may include:

  • An itchy rash that changes from small red or pink spots to raised bumps and fluid-filled blisters
  • Blisters that eventually dry out and form scabs
  • New spots appearing while older spots are already blistering or crusting
  • Fever
  • Tiredness, irritability or feeling generally unwell
  • Headache
  • Reduced appetite

The rash may appear on the chest, back or face first and then spread to other parts of the body. It may also occur inside the mouth, on the eyelids, around the genitals or on the scalp. The number of spots varies considerably. In people who have been vaccinated, chickenpox can sometimes cause only a few spots, a low or absent fever and a shorter illness. This is sometimes called breakthrough varicella.

The stages of the chickenpox rash

1. Early symptoms

Some people develop fever, tiredness, headache, reduced appetite or general discomfort a day or two before the rash. Children may have few warning symptoms, while adults can feel more unwell.

2. Red spots or bumps

The rash often begins as small discoloured spots or raised bumps. Depending on skin tone, these may look pink, red, purple, brown or darker than the surrounding skin. On darker skin, colour changes may be less obvious, so raised texture and itching can be more useful clues.

3. Fluid-filled blisters

The bumps can become small, fragile blisters containing clear or cloudy fluid. They are often intensely itchy. Chickenpox commonly appears in successive crops, so a person may have fresh spots, blisters and scabs at the same time.

4. Crusting and healing

Blisters eventually break or dry out and form scabs. In many cases, the rash heals over roughly one to two weeks, although the overall illness and marks can last longer. Scratching increases the chance of skin infection and temporary or lasting marks.

When is chickenpox contagious?

A person with chickenpox can usually spread the virus from about one to two days before the rash appears until every lesion has dried and formed a crust. Because new spots can appear over several days, it is important not to assume that someone is no longer contagious simply because some blisters have scabbed.

Chickenpox spreads mainly through close contact and respiratory particles, and through contact with fluid from the blisters. Anyone who may have chickenpox should avoid close contact with people at higher risk and follow local public-health or clinical advice about school, childcare and work attendance.

Who should contact a healthcare professional promptly?

Seek medical advice promptly if chickenpox is suspected in:

  • A pregnant person
  • A newborn or very young infant
  • An adult, particularly an adult who has not had chickenpox or vaccination
  • A person with a weakened immune system
  • A person taking medicines that suppress the immune system
  • Someone with a significant chronic medical condition

Some antiviral treatments may be considered for people at higher risk, and they are generally more useful when started early. Do not start prescription treatment without advice from a qualified clinician.

Warning signs that need urgent medical attention

Get urgent medical help if someone with a suspected or confirmed chickenpox infection develops:

  • Difficulty breathing, chest pain or a persistent severe cough
  • Confusion, unusual drowsiness, severe weakness, a stiff neck or difficulty walking
  • Repeated vomiting, severe headache or signs of dehydration
  • A rapidly worsening rash, severe pain, extensive redness, warmth, swelling or pus around lesions
  • A very high or persistent fever, or a fever that returns after initially improving
  • Eye pain, vision changes or blisters close to the eye
  • Severe abdominal pain or unusual bleeding

Emergency symptoms should be assessed according to local emergency-care guidance. Contact a healthcare service before attending in person if chickenpox is possible, because the infection can spread to others in waiting areas.

How is chickenpox different from other rashes?

Several illnesses can cause spots, itching or blisters. Possible alternatives include insect bites, eczema, contact dermatitis, impetigo, hand-foot-and-mouth disease, shingles, measles and allergic reactions. Chickenpox is more suggestive when lesions appear in crops and are present at different stages at the same time, but this pattern is not enough to confirm the diagnosis.

Measles often involves a widespread rash with fever and respiratory symptoms, while hand-foot-and-mouth disease commonly affects the mouth, hands and feet. Shingles usually causes a painful, one-sided band of blisters rather than a widespread itchy rash. These are general patterns, not a substitute for an examination or testing where needed.

What to do if chickenpox may be present

  1. Limit close contact. Keep the person away from people who could become seriously ill, especially pregnant people, newborns and those with weakened immunity.
  2. Call ahead for medical advice. Explain the symptoms before visiting a clinic or hospital.
  3. Reduce scratching. Keep fingernails short and consider clinician-approved soothing measures, such as cool baths or suitable anti-itch products.
  4. Maintain fluids. Encourage regular drinks, particularly if fever or mouth sores make eating and drinking difficult.
  5. Use medicines carefully. Ask a pharmacist or clinician which fever or itch medicines are appropriate. Children and teenagers with chickenpox should not be given aspirin because of the risk of a serious complication. Ask a healthcare professional before using ibuprofen or other anti-inflammatory medicines.
  6. Watch the skin. Increasing redness, warmth, swelling, pain or pus may indicate a secondary bacterial infection and needs medical advice.

Practical questions to consider

  • When did the fever, tiredness or rash begin?
  • Are new spots still appearing?
  • Are lesions at different stages, such as spots, blisters and scabs?
  • Has the person had chickenpox or a varicella vaccine before?
  • Has there been close contact with someone who had chickenpox or shingles?
  • Could the person be pregnant, very young, immunocompromised or taking immune-suppressing medicine?
  • Are there breathing problems, dehydration, severe pain, neurological symptoms or signs of a skin infection?

Taking clear photographs for a clinician may be helpful if this can be done without delaying urgent care. Avoid sharing photographs publicly or using them as the sole basis for diagnosis.

Frequently asked questions

Can chickenpox start without a rash?

Early symptoms such as fever, tiredness or headache can occur before the rash. Other illnesses can cause the same symptoms, so chickenpox cannot be confirmed without considering the later rash and the person's exposure, vaccination and medical history.

Can vaccinated people still get chickenpox?

Yes. Vaccination substantially changes the likelihood and typical severity of infection, but breakthrough cases can occur. They may involve fewer lesions and less fever, and the rash may not have the classic appearance.

Can chickenpox occur more than once?

Most people develop lasting immunity after infection, but repeat illness can occur rarely or the original diagnosis may have been incorrect. A later reactivation of the varicella-zoster virus causes shingles, which is a different condition.

Should chickenpox blisters be covered?

Loose, clean clothing can protect irritated skin, and covering lesions may reduce scratching or contact with blister fluid. Avoid tight or contaminated dressings, and follow professional advice if lesions look infected.

How long should someone stay away from school, childcare or work?

The usual public-health principle is to avoid close-contact settings until all lesions have dried and crusted. Rules and workplace or school policies vary by jurisdiction, so check local guidance or ask a healthcare professional.

Can adults have more severe chickenpox?

Adults may experience more significant illness and complications than many children. An adult with a new itchy blistering rash should seek medical advice, especially if they are pregnant, immunocompromised or unsure whether they have immunity.

Key point

An itchy rash that develops in crops and progresses from spots to blisters and scabs is characteristic of chickenpox, but many conditions can look similar. Avoid close contact while the person may be contagious, seek prompt advice for higher-risk people and obtain urgent care for breathing problems, neurological symptoms, dehydration or signs of a serious skin infection.

Disclaimer: This article provides general health information, not a diagnosis or personalised medical advice. Guidance and treatment options vary by country and individual circumstances. Contact a qualified healthcare professional for advice about a suspected infection, and use local emergency services for urgent symptoms.