Chickenpox

What is chickenpox?

Chickenpox, also called varicella, is a common and highly contagious infection caused by the varicella-zoster virus. It is best known for an itchy rash of small red spots that turn into fluid-filled blisters and then scab over. In many cases the illness also brings fever, tiredness, and a general feeling of being unwell for several days.

Chickenpox most often affects children, and before routine vaccination it was considered an almost universal childhood illness. However, anyone who has never had the infection or the vaccine can catch it, including teenagers and adults. The illness is usually mild in otherwise healthy children, but it tends to be more severe in adults, newborns, pregnant women, and people whose immune systems are weakened by illness or medication.

After a person recovers, the varicella-zoster virus does not leave the body. It stays inactive in nerve cells and can reactivate years or decades later as shingles (herpes zoster), a painful rash that usually appears on one side of the body. Understanding what chickenpox is, how it spreads, and how it is managed helps families make sensible decisions about care and about protecting people around them who may be at higher risk.

Chickenpox symptoms

Chickenpox symptoms usually appear about 10 to 21 days after exposure to the virus. This waiting period is called the incubation period. Some people, especially older children and adults, notice a day or two of flu-like symptoms before the rash appears. Common chickenpox symptoms include:

• Fever, which is often mild to moderate
• Tiredness and a general feeling of being unwell
• Headache
• Loss of appetite
• An itchy rash that begins as small red spots or bumps
• Spots that develop into small fluid-filled blisters (vesicles)
• Blisters that break, dry out, and form crusts or scabs
• Sores inside the mouth, on the eyelids, or in the genital area in some cases

The rash typically starts on the face, chest, and back and then spreads to the rest of the body, including the scalp. It appears in waves over several days, so a person often has spots at different stages at the same time: new red bumps, fresh blisters, and older scabs side by side. This mixed appearance is one of the features doctors look for. The number of spots varies widely from person to person. Some children have only a handful, while others are covered.

The itching can be intense and is often the most distressing part of the illness for children. Scratching can break the blisters, which raises the risk of a bacterial skin infection and can leave small scars.

Symptoms can differ by age and health status. In otherwise healthy young children the illness is usually mild and lasts about a week. Teenagers and adults often have more spots, higher fever, and a longer recovery. People with weakened immune systems may develop a more widespread rash, new spots for a longer period, and a higher chance of complications. People who have been vaccinated but still catch the virus (sometimes called breakthrough varicella) often have a much milder illness with fewer spots and little or no fever.

Causes and risk factors

The only cause of chickenpox is infection with the varicella-zoster virus, a member of the herpesvirus family. There is no other cause, and it is not related to diet, hygiene, or cold weather. Understanding chickenpox causes mainly means understanding how the virus spreads.

The virus spreads very easily from person to person in several ways:

• Through the air, in tiny droplets released when an infected person breathes, coughs, or sneezes
• Through direct contact with the fluid from chickenpox blisters
• Through contact with items freshly contaminated by blister fluid, such as bedding or clothing
• From a person with shingles, whose blisters contain the same virus, to someone who has never had chickenpox or the vaccine

A person with chickenpox is usually contagious from about one to two days before the rash appears until all the blisters have crusted over. This means the illness can spread before anyone realizes the person is sick, which is one reason outbreaks occur in schools and households.

Anyone who has not had chickenpox or the vaccine can catch it, but certain groups are at higher risk of catching the virus or of having a more severe illness:

• Children and adults who have never had chickenpox and have not been vaccinated
• People living with or caring for someone who has chickenpox or shingles
• Children in daycare or school settings where the virus is circulating
• Newborn babies, especially if the mother was not immune
• Pregnant women who are not immune, because of risks to both mother and baby
• Adults, who tend to have more severe symptoms than young children
• People with weakened immune systems, for example due to cancer treatment, organ transplant medication, long-term steroid use, or HIV
• People with certain long-term skin or lung conditions

Most people who have had chickenpox once develop lasting immunity, meaning they are unlikely to get it again. Second episodes are uncommon but can occur.

Chickenpox diagnosis

In many cases doctors can make a chickenpox diagnosis simply by examining the rash and asking about the history of the illness. The typical pattern of spots at different stages, the way the rash spread, and any known contact with someone who had chickenpox or shingles are often enough to confirm the diagnosis in an otherwise healthy child.

Your doctor may ask questions such as:

• When the first spots appeared and where they started
• Whether there was fever or other symptoms before the rash
• Whether the person has had chickenpox or the vaccine before
• Whether anyone at home, school, or work has recently had chickenpox or shingles
• Whether the person has any condition or takes any medicine that weakens the immune system

Laboratory tests are not needed for most straightforward cases, but they may be used when the rash is unusual, when the person is at high risk of complications, when the diagnosis affects decisions about pregnancy or hospital infection control, or when it is important to tell chickenpox apart from other rash illnesses. Tests that may be used include:

• PCR testing (polymerase chain reaction), a laboratory technique that detects the genetic material of the virus in a swab taken from a blister. This is generally considered the most accurate test.
• Viral culture, in which fluid from a blister is grown in a laboratory to identify the virus. This is slower and less sensitive than PCR.
• Blood tests for antibodies, which look for the body’s immune response to the virus. These are more often used to check whether someone is already immune, for example before pregnancy or before starting certain treatments, than to diagnose an active infection.

Imaging such as X-rays is not used to diagnose chickenpox itself, but a chest X-ray may be ordered if a doctor suspects pneumonia (lung infection) as a complication. Other conditions that can sometimes look similar include insect bites, hand-foot-and-mouth disease, impetigo (a bacterial skin infection), and allergic rashes, and your doctor will consider these when examining the rash.

Chickenpox treatment options

For most healthy children, chickenpox treatment options focus on comfort and on preventing complications while the body clears the virus on its own. There is no procedure or surgery for chickenpox, and antibiotics do not work against viruses. Treatment is chosen based on the person’s age, general health, and how severe the illness is.

Supportive care at home. This is the mainstay of treatment for uncomplicated chickenpox and may include:

• Rest and plenty of fluids to prevent dehydration, especially if there are mouth sores that make eating and drinking uncomfortable
• Keeping fingernails short and clean, and using cotton gloves or mittens on young children at night, to limit damage from scratching
• Cool baths, sometimes with colloidal oatmeal or baking soda added, to soothe itching
• Calamine lotion or other soothing skin products applied to unbroken spots
• Loose, soft clothing and cool room temperatures to reduce itch
• Soft, bland foods and cold drinks if the mouth is sore

Medicines for symptoms. Acetaminophen (paracetamol) is commonly used to reduce fever and discomfort. Aspirin should never be given to children or teenagers with chickenpox because of the risk of Reye’s syndrome, a rare but serious condition affecting the liver and brain. Many doctors also advise avoiding ibuprofen and similar anti-inflammatory drugs during chickenpox because of a possible link to serious skin infections, so it is best to ask a doctor or pharmacist before using them. Oral antihistamines may help with itching and sleep, but you should check with a pharmacist or doctor about suitable products and doses, particularly for young children.

Antiviral medication. Antiviral drugs such as acyclovir, valacyclovir, or famciclovir work by slowing the virus’s ability to multiply. They are not usually needed for healthy young children with mild illness. Your doctor may recommend an antiviral for people at higher risk of severe disease, such as adults, teenagers, pregnant women, newborns, people with weakened immune systems, and people with certain skin or lung conditions. Antivirals are most helpful when started early, generally within the first day or so after the rash appears. In severe cases, or for people with very weak immune systems, antiviral treatment may be given through a vein in hospital.

Treatment after exposure. For people who have been exposed to chickenpox but have not yet developed symptoms, a doctor may consider options to reduce the risk or severity of illness. These can include giving the varicella vaccine soon after exposure to a person who is otherwise able to receive it, or giving a preparation of ready-made antibodies (varicella-zoster immune globulin) to people at high risk who cannot be vaccinated, such as pregnant women without immunity, newborns, and people with weakened immune systems.

Treatment of complications. If a bacterial skin infection develops, antibiotics may be prescribed. Pneumonia, brain inflammation, or severe dehydration may require hospital admission for closer monitoring, intravenous fluids, and specialist care. In hospital settings, chickenpox is generally managed by pediatric or infectious diseases specialists; at Acibadem, for example, adult cases requiring specialist input are handled by the Infectious Diseases Department.

Living with chickenpox and outlook

For most healthy children, chickenpox is a short illness. New spots usually stop appearing after about a week, and all the blisters have typically crusted over within one to two weeks. Scabs fall off on their own over the following days. Most children feel well again within a week or two, and the vast majority recover fully without lasting problems, although some spots may leave small marks or scars, especially if they were scratched or became infected.

While someone is ill, they should stay home from school, daycare, or work until all blisters have crusted over, as they remain contagious until then. It is important to avoid contact with people who are at high risk, including pregnant women, newborn babies, and anyone with a weakened immune system. Air travel and visits to hospitals or clinics should generally be avoided during the contagious period unless a doctor advises otherwise.

Adults and people with weakened immunity are more likely to have a longer illness and a higher chance of complications, such as bacterial skin infections, pneumonia, or, rarely, inflammation of the brain (encephalitis). With prompt medical attention, most of these complications can be treated, although outcomes vary and serious illness does occur in a small number of cases.

After recovery, the virus remains dormant in the body for life. It can reactivate later as shingles, most often in older adults or people whose immune systems are weakened. A separate shingles vaccine is available for older adults and may be discussed with a doctor when appropriate. Having had chickenpox usually provides long-lasting protection against catching chickenpox again.

Frequently asked questions

What is chickenpox and how is it different from shingles?

Chickenpox is the first infection caused by the varicella-zoster virus and usually produces a widespread itchy rash with fever, most often in children. Shingles is caused by the same virus reactivating years later after lying dormant in the nerves. Shingles typically causes a painful rash limited to one side of the body in a band-like pattern, and it mainly affects older adults or people with weakened immunity. A person cannot catch shingles from someone else, but a person who has never had chickenpox or the vaccine can catch chickenpox from someone with shingles.

What are the first chickenpox symptoms to look for?

The earliest chickenpox symptoms are often fever, tiredness, headache, and loss of appetite, followed within a day or two by small red spots that quickly turn into itchy fluid-filled blisters. The rash usually starts on the face, chest, and back before spreading. In young children the rash is sometimes the very first sign. Because these early symptoms overlap with many other childhood illnesses, a doctor may be needed to confirm the cause.

What are the main chickenpox causes and how does it spread?

The only cause is the varicella-zoster virus. It spreads through the air when an infected person coughs, sneezes, or breathes, and through direct contact with fluid from blisters. A person can pass on the virus from one to two days before the rash appears until all blisters have crusted over, which is why it spreads so easily in households and schools before anyone knows they are sick.

How is a chickenpox diagnosis confirmed?

In most cases a doctor confirms chickenpox by looking at the rash and asking about symptoms and recent contacts. The mix of new spots, blisters, and scabs at the same time is quite characteristic. When there is doubt, or when the person is at higher risk, a swab from a blister can be sent for PCR testing to detect the virus, and blood tests can check for antibodies that show past infection or immunity.

What are the chickenpox treatment options for adults?

Adults tend to have more severe chickenpox than children, so doctors more often recommend antiviral medication such as acyclovir or valacyclovir, ideally started within the first day or so of the rash. Supportive measures such as rest, fluids, fever control with acetaminophen, and itch relief are also important. Adults should watch closely for warning signs such as breathing difficulty or a persistent high fever, since complications like pneumonia are more common in this age group.

Can chickenpox be prevented?

Vaccination is the main way to prevent chickenpox. The varicella vaccine is given in two doses in many countries as part of routine childhood immunization and is also recommended for older children and adults who have never had the disease. It is not suitable for everyone, for example pregnant women and some people with weakened immunity, so a doctor can advise on individual circumstances. Avoiding close contact with infected people during the contagious period also reduces spread.

Is chickenpox dangerous during pregnancy?

Chickenpox during pregnancy can be more serious for the mother, who has a higher risk of pneumonia, and in some circumstances it can affect the developing baby or the newborn. A pregnant woman who is not sure she is immune and who has been exposed to chickenpox should contact her doctor or midwife promptly, because preventive treatment may be available and is most effective when given soon after exposure.

When to see a doctor

Many children with chickenpox can be cared for at home, but it is sensible to contact a doctor when the diagnosis is uncertain, when the person is an adult, a newborn, pregnant, or has a weakened immune system, or when you are unsure how to manage symptoms. If someone in these higher-risk groups has been exposed to chickenpox but is not yet ill, early medical advice matters because preventive treatment is time-sensitive.

Seek urgent medical attention if you notice any of the following red-flag warning signs:

• Difficulty breathing, fast breathing, or chest pain
• Fever that is very high, lasts more than a few days, or returns after settling
• Spots or the skin around them that become very red, swollen, warm, painful, or leak pus, which may indicate a bacterial infection
• Severe headache, stiff neck, sensitivity to light, or repeated vomiting
• Unusual drowsiness, confusion, difficulty waking, or a seizure
• Problems with walking, balance, or coordination
• Signs of dehydration, such as very little urine, a dry mouth, or no tears when crying
• Rash that spreads into the eye, or eye pain and blurred vision
• Bleeding into the skin, or spots that look like bruises
• A rash in a newborn baby less than a month old

Call emergency services or go to the nearest emergency department if breathing difficulty, seizures, or a marked change in alertness occur. When visiting a clinic or hospital with suspected chickenpox, it helps to let staff know in advance so they can take steps to protect other patients who may be vulnerable.