Burns are injuries to the skin and underlying tissues that can lead to pain, blistering, swelling and loss of skin. They are usually caused by heat from fire, steam or hot liquids.

However, they might also result from chemicals (acids), ultraviolet radiation (sun exposure), radiation and electricity.

Q: How are burns classified?

A: Burns are classified as minor, moderate or severe, based on two factors: the depth of the burn and the total area burned.

The depth of injury is described as first, second, or third degree.

• First-degree burns affect only the top layer of skin (epidermis). These are described as superficial burns. First-degree burns are red, swollen and painful. The burned area whitens when lightly touched but does not develop blisters.

• Second-degree burns extend into the middle layer of skin (dermis). Second-degree burns are pink or red, swollen and painful, and they develop blisters that might ooze a clear fluid. The burned area might whiten when touched.

• Third-degree burns extend through all three layers of skin (epidermis, dermis, and fat/muscle). These burns also harm the sweat glands, hair follicles and nerves. Third-degree burns usually are not painful because the nerves have been destroyed. The skin becomes leathery and may be white, black or bright red. The burned area does not whiten when touched, and hairs can easily be pulled from their roots without pain.

The total burn area is classified in categories.

Minor burns: All first-degree burns, as well as second-degree burns that involve less than 10% of the body surface, usually are classified as minor.

Moderate and severe burns: Burns involving the hands, feet, face or genitals, second-degree burns involving more than 10% of the body surface area, and all third-degree burns involving more than 1% of the body are classified as moderate or severe.

Q: What is the best treatment for burns?

A: First-aid measures at home might be all that is necessary to treat small, shallow burns that are clean. Running cold water over the burn can help relieve pain.

Additionally, covering the burn with an over-the-counter antibiotic ointment and a nonstick, sterile bandage can help prevent infection.

If the burn has the following traits, consult a physician for immediate treatment:

• The burn is larger than the size of the person’s open hand

• Blisters appear at the site of the burn

• The burn involves the face, hand, foot, genitals or skin folds

• The wound is not entirely clean

• Pain persists longer that one day after the burn

A serious burn might require admission to a hospital or frequent re-examination at a doctor’s office, possibly as often as daily for the first few days.

Q: What are the complications of a burn?

A: Minor burns are usually superficial and do not cause significant complications. First- and some second-degree burns heal in days to weeks without scarring. Second-degree and third-degree burns can cause scar tissue to form.

Deep second-degree and small third-degree burns take weeks to heal and usually cause scarring. Most require skin grafting. Severe burns (and some moderate burns) can cause serious complications due to extensive fluid loss and tissue damage. These complications might take hours or days to develop.

If you’ve experienced a burn that you think needs professional treatment, call a dermatologist.

Dr. Oswald Lightsey Mikell, certified by the American Board of Dermatology and the American Board of Cosmetic Surgery, is the owner of Dermatology Associates of the Lowcountry.