What are blisters?
Blisters are pockets of fluid that form on the skin, often as a reaction to rubbing, friction, or burns.
A blister is formed by the body's defence mechanisms to help protect the skin against further damage and to promote healing.
Some blisters are caused by conditions such as chickenpox and impetigo.
Blister image: iStock
What causes blisters?
Blisters are caused by several things:
- Friction: Blisters can develop when a surface rubs against exposed skin, such as a tool handle against the hand, or a new pair of shoes against the heel. Unlike corns and calluses, which develop from prolonged rubbing, friction blisters come from brief, intense contact.
- Burns: Flames, steam, or contact with a hot surface can cause blisters, as can severe sunburn or exposure to other types of radiation.
- Contact with irritants: Skin may blister when it comes in contact with chemical irritants, cosmetics, and many plant and animal toxins. This is called contact dermatitis.
- Drug reactions: Many people develop blisters as a reaction to certain oral and topical drugs. If you develop a blister while on medication, you should seek medical advice.
- Autoimmune diseases: Of the various autoimmune diseases known to cause blistering, three are most common. Pemphigus vulgaris, a potentially fatal skin disorder, causes blisters in the mouth that sometimes spread to the head and other parts of the body; the painful blisters become raw and crusted before bursting. Bullous pemphigoid causes less severe eruptions that heal faster and are not life-threatening; this condition is seen mainly in the elderly. Dermatitis herpetiformis causes small, itchy blisters; it is a chronic condition that usually starts in early adulthood.
- Infection: Blisters are a common symptom of many infectious illnesses, including chickenpox, cold sores, shingles, and a skin infection called impetigo.
Blisters, corns and calluses
Corns and calluses are related problems to blisters on the skin.
- Corn: A build-up of hard skin near a bony area of a toe or between toes. Corns may be caused by pressure from shoes that rub against the toes or cause friction between them.
- Callus: A build-up of hard skin, usually on the underside of the foot. Calluses are caused by an uneven distribution of weight, generally on the bottom of the forefoot or heel. They can also be caused by improperly fitting shoes or a skin abnormality. It's normal to have some calluses on the soles of your feet.
How are blisters, corns and calluses treated?
Don't "pop" the blister; the skin covering the blister helps protect it from infection. Gently wash the area with mild soap and water or a cleansing towel and then apply antibacterial cream. Cover it with gauze and secure with hypoallergenic tape to help protect the skin and prevent infection. Change the dressing at least once a day and wear different shoes until the blister heals.
Don't try to cut the corn or remove it with a sharp object. After you have a bath or shower, while your skin is still soft, use a pumice stone or an emery board to smooth and gently remove the build-up of tissue. Move the emery board or pumice stone in one direction only. You can also use cushioned or medicated pads.
Don't try to cut the callus or remove it with a sharp object. After your bath or shower, use a pumice stone to gently remove the build-up of tissue. You can also use cushioned pads and in-soles. Your doctor may recommend treatments to soften the callus.