Blisters are small bubbles on the skin filled with a clear fluid called serum. They form when the outer layer of skin has been damaged.
Sometimes blisters become filled with blood (blood blisters) which form when a blood vessel breaks near the surface of the skin leaking blood between the layers of skin.
If a blister becomes infected it may become red, painful and fill with yellow or green pus.
What causes blisters?
Blisters are caused by friction to the skin, heat (from scalding or sunburn), from contact with skin irritants, from medical conditions such as chickenpox, from extreme cold, as a reaction to some drugs or due to autoimmune diseases.
A blister forms when friction or heat, for example, creates a tear between the upper layer of the skin (the epidermis) and the layers beneath this. When this happens, the surface of the skin remains intact but is pushed outwards as serum collects in the newly created space between the layers.
How to treat blisters
Most blisters heal naturally without complications as the unbroken skin around the blister provides a natural barrier against infection. Within a week new skin usually grows beneath the blister, the fluid gets slowly reabsorbed and skin on top of the blister dries and peels off.
- Burst the blister. It may be tempting but it will increase your risk of infection.
- Pick at the skin. If the blister bursts by itself don’t peel off the dead skin. Instead, allow the fluid to drain, then cover it with a dry, sterile dressing. Change the dressing daily.
- Seek medical attention if the blister becomes very painful, keeps recurring, develops somewhere uncomfortable such as on the eyelids, or starts weeping pus, or becomes inflamed. An infected blister can be treated with antibiotics.
Alternative Remedies & Self-help
Most blisters can be prevented with common sense. Comfortable shoes can prevent blisters forming on your feet during exercise, gloves can protect again skin irritants or friction, sun-screen can help you avoid blisters from the sun.