Blisters are caused by a variety of things, but most often, they result from friction or minor burns. Blisters are formations on the skin wherein the outer layer swells up due to fluid. Oftentimes, these kinds of blisters will heal on their own. A new layer of skin grows underneath the fluid and it eventually dries out.
The initial reaction of many people is to pop a blister. This is not recommended as the outer skin and the fluid actually keeps the blister sterile, avoiding infection. Once the new layer of skin has grown, the outer skin should shed on its own. However, if you really have to pop your blister, follow these steps.
First, make sure that the area around the blister is clean. Wash it with soap and warm water, and then further sterilize it with alcohol. Get a needle or razor blade and sterilize it as well. You can then prick or cut the outer skin of the blister really gently, and then squeeze the fluid slowly. The fluid should be clear - almost watery. Once you have drained the blister, do not peel away the outer skin. Leave it there as a protective cover until the blister totally dries out.
If the fluid that comes out is thick and yellowish, it may be a sign that the blister is infected. If this is the case, putting some antibiotic cream will help. If the area is really painful, red, and swollen, then you may have to visit a doctor to have it properly treated.