A blister is a raised area of skin with often clear fluid inside. Sometimes the fluid is bloody. A blister can occur when the skin is damaged. Blisters can hurt when they are pressed, or if they break open.
Blisters can be caused in many ways. This can happen if the skin is rubbed too hard or often. Or they can occur if the skin is hurt by a burn, an allergen such as poison ivy, the sun, a virus, or even a medicine. Some skin diseases can also cause blisters.
Most blisters need little treatment. They often dry up and go away in a few days to weeks after the cause is stopped. A blister may need to be cleaned. A broken (open) blister may be bandaged to prevent infection. Blisters caused by insect bites or medicine reactions may be more serious. These should be looked at by a healthcare provider.
Your healthcare provider may prescribe pain medicine. He or she may also prescribe an antibiotic cream or ointment to put on an open blister. Follow all instructions when using these medicines.
Follow all instructions on how to care for the blister. If a bandage was put on, change the bandage as instructed.
If the blister breaks, the area will leak a clear or sometimes a bloody fluid for a day or two. Wash the area with soap and water every day or as advised by your healthcare provider. Don't remove the "roof" of the blister. This part protects the raw skin as it heals.
You may use over-the-counter pain medicines to control pain, unless another medicine was prescribed. If you have chronic liver or kidney disease, talk with your healthcare provider before using these medicines. Also talk with your provider if you've had a stomach ulcer or gastrointestinal bleeding.
Follow up with your healthcare provider, or as advised.
When to seek medical advice
Call your healthcare provider right away if any of these occur:
Fever of 100.4°F (38°C) or higher
Redness or swelling that is new or gets worse
Foul-smelling fluid leaking from the blister
Pain doesn’t go away, or gets worse
Increase in size of the blister
Blister doesn’t get better after several days
New blisters appear