Burns to the skin are caused by heat or chemicals. Fire is the most common source of heat burns, but they can also come from contact with a hot surface, steam or hot liquids. Chemical burns may arise from household cleaning products, industrial chemicals or chemicals used in armed conflict.
Types of Burns
According to the University of Maryland Medical Center Dermatology Health Guide, human skin comprises several layers, including the epidermis (made up of the stratum corneum, keratinocytes and basal layer), the dermis and the subcutis. Burns are categorized according to how deep they reach into these layers of skin:
First-degree burns affect only the topmost layer of skin. They will usually be red and painful, and may sometimes be mildly swollen.
Second-degree burns, sometimes called partial-thickness burns, reach down into the dermis. They are characterized by swelling, blisters, bright red and splotchy skin, wet or oozing areas and pain. They can be further subdivided into superficial partial-thickness burns and deep partial-thickness burns, depending on how far they reach into the dermal layer.
Third-degree or full-thickness burns, which affect all the layers of skin and sometimes even the muscle and fat layers, are the most serious type of burn. However, they are actually the least painful. The nerve endings---along with the sweat glands and hair follicles---are actually burned away along with the subcutis layer of skin, so sensation in the area is lost. The skin of this type of burn may appear charred, leathery, or white and hardened.
Severity of Burns
Burns may be further categorized as minor or major. Some health care organizations also include a moderate category. The determination of the severity of the burn depends on both the depth (degree) of the burn and the percentage of body area covered by the burn.
In general, all first-degree burns are considered minor, as are second-degree burns that aren't bigger than a couple of inches in diameter. However, according to the Mayo Clinic, "If the burned area is larger or if the burn is on the hands, feet, face, groin or buttocks, or over a major joint, treat it as a major burn and get medical help immediately."
Third-degree burns are always considered major.
Other Sources of Burns
Radiation, including sunlight, and electricity may also cause burns to the skin. Sunburn is a common cause of quite painful skin burns. Though usually minor, this type of burn could easily be moderate or even major, depending on how large an area it covers on the body.
Electrical burns may also cause muscle pain or spasms, due to the effect of the electricity on the muscle itself.
The Most Painful Burns
Second-degree skin burns are almost always more painful than first- or third-degree burns, no matter what the cause of the burn. The most painful skin burns are second-degree burns that cover more than 10 percent of the body or are in particularly sensitive areas, such as the groin or hands.
