A rash composed of numerous red, pimple-like blisters is the most obvious and well recognized symptom of chickenpox. It typically appears as red, superficial spots about two to four days after the appearance of certain non-specific symptoms (e.g., fever, loss of appetite). These spots usually first appear in the torso area, often spreading to the head, face and limbs before eventually becoming blisters.

Some people with chickenpox may develop lesions in their ears and mouth or on their genitals in rare instances. A mild fever is common with chickenpox, as are flu-like symptoms such as stomachaches, mild headaches, sore throat, achiness, fatigue, runny nose or congestion and a feeling of irritability.

The amount of blisters can range from a few to several hundred depending on the age and response of the patient to varicella–zoster virus (VZV). The spots redden and enlarge to about ¼ to ½ of an inch in diameter (6.35 to 12.5 millimeters) as they change to blisters. The blisters are usually surrounded by narrow red halos at this stage. After several days, the blisters mature and break open, forming sores which eventually crust over. Most blisters heal within about two weeks without scarring.  The red spots generally continue to form every day for about five to seven days. While there are several stages of development, the rash can be in all stages of development simultaneously.

Most cases of the disease are mild and heal without any lasting effects. However, medical attention may be required during a chickenpox infection if certain medical conditions develop, including:

• Fever above 103 degrees Fahrenheit (39.44 degrees Celsius)
• Seizures
• Coughing and difficulty breathing
• Confusion or disorientation
• Blister rash near the eye
• Sustained dehydration or vomiting
• Severe headache
• Skin infections, including:
  
• Blisters leaking yellow or green fluid
• Additional pain, redness or inflammation in the area around a chickenpox blister

A person is generally no longer considered contagious, and can return to school or work when they are no longer developing new red spots and any existing spots have dried.