Health Topics for Prepare for Emergencies

Department of Emergency Medicine

Emergency Medical Services Learning Resources Center

Blisters

A blister is a bubble of fluid under the skin. It may be filled with clear fluid, blood, or pus. A blood blister is caused by pinching or a large amount of trauma, such as catching a finger in a door. Friction blisters are the result of rubbing something against your skin, such as tight shoes or a rake rubbing against the palm of your hand. Other causes of blisters include:

• second-degree burns and sunburns
• viral infections, such as Herpes
• harsh chemicals
• poisonous plants, such as poison ivy

The area surrounding the blister may be red, swollen and sore. Most blisters last about 3 to 7 days. If a blister gets infected, it may be more painful and hot to touch. You may even have a fever.

You should not break a blister. Skin helps keep bacteria out. Blisters usually drain by themselves. Once the skin is very dry and painless, you can carefully trim it off.

Large blisters may need to be drained. It is important to do this in a way that does not cause an infection. Always use a sterilized needle. You can sterilize it by heating with a flame until it is red hot; then allow it to cool without touching anything. Or, you can sterilize it by putting it in rubbing alcohol. Carefully stick the end of the needle in the edge of the blister in several places to drain the fluid. Clean the area with mild soap and water. If it breaks, apply an antibiotic ointment (available at your drugstore) and cover with a bandage.

You can protect the blister by putting a "blister donut" over it. Buy a piece of moleskin at your drugstore. Cut a hole in the center that is a little bigger than the blister. Place the hole of the moleskin over the blister. Cover the moleskin with a bandage.

To prevent blisters:

• avoid wearing shoes that are wet, too tight, or too loose
• wear 2 pairs of socks to protect your skin
• wear gloves when doing activities, such as raking or shoveling snow
• put Vaseline on spots that tend to rub or use foot powder
• cover areas that frequently get blisters with tape or a bandage
• avoid long exposures to the sun (if you have to go in the sun, use a sunscreen and wear protective clothing)
• avoid getting harsh chemicals on your skin; wear gloves
• learn to identify poisonous plants and protect skin areas with clothing

If you have a blister that becomes red, painful, full of pus, or it does not heal in a few days, see your healthcare provider. This is especially important if you are a diabetic.

Last Reviewed 2005

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIL File PREP3199.rf2 VRS# 7413 Data Version 7.0 Copyright 1998, 2003 McKesson Health Solutions LLC. All rights reserved.