Chickenpox causes an itchy, blistering rash that typically appears 10 to 21 days after exposure to the varicella-zoster virus. Before the rash shows up, you may notice a fever, fatigue, headache, and loss of appetite. The full illness usually lasts 4 to 7 days, though the rash itself can persist for up to 10 days as new spots continue to form.
Early Symptoms Before the Rash
One to two days before the rash appears, you may develop a mild fever, general tiredness, loss of appetite, and a headache. In children, these early warning signs are often so mild they go unnoticed, and the rash itself is frequently the first obvious sign of infection. Adults tend to have a more noticeable run of these early symptoms and generally feel sicker overall before the spots arrive.
How the Rash Develops
The rash usually starts on the chest, back, and face before spreading across the entire body. It moves through three distinct stages:
- Raised red bumps (papules) that break out over several days.
- Small fluid-filled blisters (vesicles) that form within about a day, then break open and leak.
- Crusts and scabs that cover the broken blisters, taking a few more days to heal.
Because new bumps keep appearing for several days, you’ll typically see all three stages at the same time: fresh red bumps alongside fluid-filled blisters and older, crusted-over spots. This overlapping pattern is one of the hallmarks that distinguishes chickenpox from other rashes. The classic individual lesion is sometimes described by doctors as looking like “a dewdrop on a rose petal,” a small, clear blister sitting on a red base.
The rash is intensely itchy. Most people develop anywhere from 200 to 500 lesions over the course of the illness, though this number varies widely.
Symptoms in Adults vs. Children
Children usually have a milder course. The rash may be the first and most prominent symptom, with only a low-grade fever and slight fatigue alongside it. Adults, on the other hand, are more likely to experience a higher fever, stronger body aches, and more severe fatigue in the days before and during the rash. Adults also tend to develop more lesions and are at greater risk for complications like pneumonia.
Symptoms in Vaccinated People
If you’ve been vaccinated and still catch chickenpox (a “breakthrough” case), your symptoms are typically much milder. The rash often consists of fewer lesions, and those lesions may stay flat and red rather than progressing to the classic fluid-filled blisters. Fever is less common, and the illness tends to resolve faster than in unvaccinated individuals.
Symptoms in Immunocompromised People
People with weakened immune systems, including those on immunosuppressive medications or living with HIV, can develop an atypical and more severe form of chickenpox. The rash may involve significantly more lesions, and new spots can continue appearing for more than 7 days instead of the usual 4 to 7. Lesions may also show up in unusual locations like the palms of the hands and soles of the feet, and they can become hemorrhagic (blood-filled) rather than clear.
In children with HIV and low immune cell counts, the rash can persist for weeks or even months. The blisters may turn into non-healing ulcers that become crusty and thickened over time, rather than following the normal healing pattern.
When Chickenpox Is Contagious
You’re contagious starting about 1 to 2 days before the rash appears, which is part of what makes chickenpox so easily spread. You remain infectious until every blister has crusted over completely. The average incubation period is 14 to 16 days from the time of exposure, though it can range from 10 to 21 days. This means you could be exposed and feel perfectly fine for two weeks before any symptoms develop.
Warning Signs of Complications
Most cases of chickenpox resolve on their own, but certain symptoms suggest a more serious problem is developing. Watch for a fever that spikes above 102°F (39°C) or returns after initially going away, as this can signal a secondary bacterial infection in the skin. Redness, warmth, or swelling spreading outward from the base of a blister also points to bacterial infection.
Difficulty breathing or a persistent cough during chickenpox can indicate viral pneumonia, which is more common in adults, newborns, and immunocompromised individuals. Severe headache, confusion, difficulty walking, stiff neck, or unusual sleepiness may point to neurological involvement. Any of these symptoms warrant immediate medical attention.