Blisters are fluid-filled bumps that look like bubbles on the skin. You may develop a blister on your foot when you wear new shoes that rub against your skin or on your hand when you work in the garden without wearing gloves. Home treatment is often all that is needed for this type of blister.
Other types of injuries to the skin that may cause a blister include:
Burns from exposure to heat, electricity, chemicals, radiation from the sun, or friction.
Cold injuries from being exposed to cold or freezing temperatures.
Some spider bites, such as a bite from a brown recluse spider. Symptoms of a brown recluse spider bite include reddened skin followed by a blister that forms at the bite site, pain and itching, and an open sore with a breakdown of tissue (necrosis) that develops within a few hours to 3 to 4 days following the bite. This sore may take months to heal.
Pinching the skin forcefully, like when a finger gets caught in a drawer. A blood blister may form if tiny blood vessels are damaged.
Infection can cause either a single blister or clusters of blisters.
Chickenpox (varicella) is a common contagious illness that is caused by a type of herpes virus. Chickenpox blisters begin as red bumps that turn into blisters and then scab over. It is most contagious from 2 to 3 days before a rash develops until all the blisters have crusted over.
Shingles, often seen in older adults, is caused by the same virus that causes chickenpox. Shingles blisters look like chickenpox, but they usually develop in a band on one side of the body.