Chickenpox in adults is significantly more dangerous than in children. The hospitalization rate for adults is roughly 14 per 1,000 cases, compared to 1 to 2 per 1,000 in healthy children. The fatality rate tells a similar story: about 21 per 100,000 adult cases versus 1 per 100,000 in children ages 1 through 14. If you’re an adult who never had chickenpox or the vaccine, here’s what you’d be facing.
More Intense Symptoms From the Start
In children, chickenpox typically means a mild fever (up to about 102°F), some fatigue, and a rash that runs its course in a few days. Adults get all of that, but worse. The fever tends to run higher, the fatigue hits harder, and a prodrome period of fever and general malaise often kicks in one to two days before the rash even appears. That means you’ll likely feel sick before you see a single spot.
The rash itself follows the same pattern as in children, progressing from red bumps to fluid-filled blisters to crusted scabs over the course of several days. But adults tend to develop more lesions, and the overall illness lasts longer. You’re considered contagious starting one to two days before the rash appears and remain so until every single blister has crusted over, which can mean a week or more of isolation from others.
Pneumonia Is the Biggest Risk
The complication that sends the most adults to the hospital is viral pneumonia, and it’s not rare. Estimates put the incidence of varicella pneumonia somewhere between 16% and 33% of adult cases. This isn’t a mild chest cold. It can progress to fluid buildup in the lungs and, in severe cases, organ failure. Fatality rates for varicella pneumonia range from 20% to 50%, making it by far the most life-threatening complication of adult chickenpox. In children with healthy immune systems, this type of pneumonia is uncommon.
Symptoms to watch for include shortness of breath, chest pain, rapid breathing, or a cough that develops a few days into the illness. These signs warrant immediate medical attention.
Neurological Complications
Chickenpox can also affect the brain, and adults appear more vulnerable to certain neurological problems than children. Encephalitis (inflammation of the brain) is the most common neurological complication in adults, typically showing up about five to six days after the skin lesions appear. Symptoms can include confusion, severe headache, seizures, or difficulty with coordination.
A retrospective study of 20 adult patients with neurological complications from chickenpox found that half developed encephalitis. Others experienced blood clots in the brain’s veins, strokes, or a condition called cerebellitis that causes problems with balance and coordination. Children, by contrast, more commonly develop the cerebellar form, which tends to resolve on its own. In adults, encephalitis is the bigger concern and can cause lasting damage.
Skin Infections and Scarring
Every chickenpox blister is an open door for bacteria. Secondary bacterial infections are one of the most common complications at any age, showing up as cellulitis, impetigo, or deeper skin infections. Adults tend to get deeper, more prominent scars than children, partly because the lesions are more numerous and partly because the inflammatory response is stronger.
Keeping your nails short (or wearing gloves at night) reduces scratching damage and limits the bacteria you introduce into open blisters. Washing the skin daily with warm water also helps prevent bacterial infections from taking hold. Resist the urge to pick at scabs. Once a blister is infected, the risk of permanent scarring goes up substantially.
Risks During Pregnancy
Chickenpox during pregnancy poses a serious threat to the developing baby. When a pregnant person contracts varicella during the first or second trimester, there is an estimated 0.4% to 2.0% chance the newborn will develop congenital varicella syndrome. This condition can cause underdeveloped limbs, an abnormally small head, skin and eye abnormalities, intellectual disability, and low birth weight. The risk is highest during the first 20 weeks of pregnancy.
Infection close to delivery is dangerous in a different way. If a mother develops chickenpox within five days before or two days after giving birth, the newborn can contract a severe, sometimes fatal form of the disease because the baby hasn’t had time to receive protective antibodies.
Antiviral Treatment Works Best Early
Antiviral medication can shorten the illness and reduce the severity of symptoms, but timing matters. Treatment is most effective when started as soon as possible after the first sign of rash, ideally within 24 hours. For adults, the standard course runs five days. Starting treatment late still offers some benefit, but the window for maximum effectiveness is narrow.
Beyond antivirals, treatment is mostly supportive: managing fever, staying hydrated, and using calamine lotion or cool baths to ease itching. Adults often need to take time off work for at least a week, sometimes longer if complications develop.
The Shingles Connection
Once you recover from chickenpox, the virus doesn’t leave your body. It retreats into nerve cells and stays dormant, sometimes for decades. Later in life, it can reactivate as shingles, a painful blistering rash that follows the path of a single nerve. This happens regardless of whether you had chickenpox as a child or an adult.
Interestingly, being re-exposed to the virus after your initial infection appears to boost your immunity against shingles. Research published by BMJ found that adults who were exposed to a child with chickenpox in their household were about 33% less likely to develop shingles over the following two years. That protective effect faded only slightly over time, with a 27% reduction still holding 10 to 20 years later. This doesn’t mean you should seek out exposure, but it helps explain why shingles rates have risen as childhood vaccination has reduced the amount of virus circulating in the community.
Vaccination Still Works for Adults
If you’ve never had chickenpox and were never vaccinated, the vaccine is still available and effective. Among healthy adolescents and adults, about 78% develop protective antibodies after one dose. After a second dose given four to eight weeks later, that number jumps to 99%. Overall, the vaccine is estimated to be 70% to 90% effective at preventing infection entirely, and 90% to 100% effective at preventing moderate to severe disease.
That second number is the important one. Even if a vaccinated person does catch chickenpox (called “breakthrough varicella”), the illness is almost always mild, with fewer lesions, lower fever, and a much shorter course. For adults who aren’t sure whether they had chickenpox as a child, a blood test can check for existing immunity before deciding on vaccination.