Blisters

A blister is a fluid-filled area under the top layer of skin. Blisters may also develop on a mucus membrane.


Causes/associated factors
Blisters are typically caused by physical trauma, such as a particular area being crushed or pinched. Any activity that rubs the affected skin repeatedly, such as raking leaves or wearing poorly fitting shoes, may cause the skin to separate into two layers. The resulting space may then fill with fluid. In other cases, blisters are caused by factors such as:
contact dermatitis (inflammation of the upper layers of skin)
sunburn
insect bites
second degree burns
certain viral infections, such as herpes
Sometimes blisters are a side effect of a medication. Certain medical conditions may also have blisters as a symptom, including chronic blistering diseases of the skin.


Signs/symptoms
You'll notice a raised, usually circular, fluid-filled area on the skin. The area may be tender, and the fluid can be clear or bloody. Blisters may be as small as the head of a pin or up to several inches in diameter.

Diagnosis
Blisters are typically diagnosed through your own observation of symptoms.

Treatment
Left alone, a closed blister will typically heal on its own. Leave the skin of the blister in place to protect the area underneath and decrease the risk of infection. You may cover the area with a nonstick dressing or adhesive bandage. Change the bandage once or twice a day, or more often if needed. A blister covered with skin will typically dry up and peel off within one to two weeks.
For a painful blister caused by friction, you may use a sterilized needle to make a small hole in the blister and gently drain the fluid. Sometimes, a blister will burst on its own. If the blister is no longer covered with skin, wash the affected area with water and a mild, nonscented soap twice a day. Apply an over-the-counter antibiotic ointment (such as Bacitracin or Polysporin) and cover it with a clean bandage. Once the skin has dried, you may trim the dead skin with a scissors that's been soaked in alcohol. Or, leave the dead skin alone to dry and eventually flake off on its own. Avoid bumping or rubbing the site to prevent tearing the adjacent intact skin.

Consult your doctor if you have a blister that:

forms in the mouth, eyes or around the genital area
suddenly appears, especially if you have diabetes or are elderly
occurs while you're taking a new medication
seems to be associated with an underlying infection
occurs with no known cause

Complications
An open blister can lead to a secondary bacterial infection. Seek medical attention if you notice any of the following infection warning signs:
increased redness
increased tenderness
discharge or pus
warmth in the surrounding skin
red streaks from the blister area

Pregnancy-specific information
If you develop unexplained blisters during pregnancy or shortly after childbirth, consult your doctor. These blisters may indicate conditions such as herpes gestationis (also called pemphigoid gestationis) or impetigo herpetiformis. Without prompt medical treatment, both conditions may cause complications for either you or your baby.

Senior-specific information
Older adults often have decreased immune systems, which may increase the risk of a secondary infection developing at the site of a blister. Chronic diseases, which are also more prevalent among older adults, may contribute to longer healing times and weakened immune systems.

Prevention
To prevent blisters, keep the following self-care measures in mind.
Wear gloves when working with your hands.

Wear protective clothing and eye goggles when you're exposed to chemicals or harsh cleaning agents.

Wear oven mitts to protect your hands and forearms from burns while you're cooking.

Wear properly fitting shoes and socks to avoid friction to the feet. Shoes should fit snugly, but make sure there's enough room in the toes and forefoot.

Don't wear damp shoes or socks. Moisture encourages blisters to form.

Choose socks made from materials that wick moisture away from your skin, such as acrylic. Avoid tube socks, which have a poorer fit and tend to rub on the skin more than other types of socks. Some people choose to avoid socks completely.

Break in new shoes slowly. Gradually increase the length of time you spend wearing the shoes each day. Neoprene or gel insoles inside your shoes may help as well

tape areas that are prone to blisters before they develop.

Wear appropriate clothing for recreational or sports activities, and use exercise equipment properly.