A blister is a bubble of fluid under the outer layer of skin. The fluid may be clear or filled with blood or pus. There are many possible causes of blisters including a burn, disease, an allergic reaction, or from your skin rubbing against something. Blisters caused by your skin rubbing against something are called friction blisters and most commonly occur on feet or hands.
You may get blisters on your feet if your shoes or socks don't fit well. Athletes and hikers often get foot blisters. You may also get blisters on your hands when you work with tools for a long time (such as digging or raking). Gymnasts and baseball players often get blisters on their hands or fingers.
Blisters usually happen when you start a new sports season or exercise program, when you wear new shoes, or when the weather is hot and humid.
When the skin gets irritated, fluid collects underneath the outer layer of skin. This can be quite painful. The surrounding area may be red, sore, or swollen. Blisters can be very small or quite large.
Most blisters are filled with clear fluid. If the fluid is bloody it usually means that a lot of force caused the blister. If the blister is filled with pus it is probably infected. The blister as well as the tissue around the blister can get infected. Infected blisters are very painful, they may be swollen and warm to touch and you may even have a fever.
Your healthcare provider will ask about your symptoms and examine you.
It is best to leave most small blisters alone. Keep them clean and covered with an antibiotic ointment and a bandage. Put a little petroleum jelly around the blister or the part of a shoe that causes the irritation so there is less rubbing of the blister.
You can buy moleskin at a drug store to protect the blister. Cut a round piece of moleskin that is bigger than the blister and cut a hole in the center. Then put the moleskin on your skin with the hole over the blister. Cover the moleskin with a bandage.
Blisters usually drain by themselves and last about 3 to 7 days. The overlying skin is a natural protective layer. Leave it in place until it is very dry and the underlying skin has become tough and painless. Then you can trim off the layer of dry skin.
Large blisters may need to be drained. It is important to do this in a way that does NOT cause an infection. If you do this yourself, always use a sterilized needle to drain a blister. The needle should be sterilized by heating it with a flame until it is red hot and then allowed to cool. You can also sterilize a needle with rubbing alcohol. Use the needle to puncture the edge of the blister in several places. Make the punctures wide enough so they do not reseal. Cover the area with antibiotic ointment and a bandage.
If a blister gets infected, you need to see your healthcare provider. Your provider may prescribe an antibiotic for the infection.
Contact your healthcare provider if you have new or worsening symptoms.
Follow these guidelines to have less rubbing against your skin:
