burn burn a burn is an injury to skin, or other tissues, caused by heat, cold, electricity, chemicals, friction, or ultraviolet radiation (like sunburn). most burns are due to heat from hot liquids (called scalding), solids, or fire. burns occur mainly in the home or the workplace. in the home, risks are associated with domestic kitchens, including stoves, flames, and hot liquids. in the workplace, risks are associated with fire and chemical and electric burns. alcoholism and smoking are other risk factors. burns can also occur as a result of self-harm or violence between people (assault). this article is about the injury. for other uses, see burn (disambiguation). burnsecond-degree burn of the handspecialtydermatology critical care medicine, plastic surgerysymptomsfirst degree: red without blisterssecond degree: blisters and painthird degree: area stiff and not painful fourth degree: bone and tendon losscomplicationsinfectiondurationdays to weekstypesfirst degree, second degree, third degree, fourth degreecausesheat, cold, electricity, chemicals, friction, radiationrisk factorsopen cooking fires, unsafe cook stoves, smoking, alcoholism, dangerous work environmenttreatmentdepends on the severitymedicationpain medication, intravenous fluids, tetanus toxoidfrequency67 million (2015)deaths176,000 (2015) burns that affect only the superficial skin layers are known as superficial or first-degree burns. they appear red without blisters and pain typically lasts around three days. when the injury extends into some of the underlying skin layer, it is a partial-thickness or second-degree burn. blisters are frequently present and they are often very painful. healing can require up to eight weeks and scarring may occur. in a full-thickness or third-degree burn, the injury extends to all layers of the skin. often there is no pain and the burnt area is stiff. healing typically does not occur on its own. a fourth-degree burn additionally involves injury to deeper tissues, such as muscle, tendons, or bone. the burn is often black and frequently leads to loss of the burned part. burns are generally preventable. treatment depends on the severity of the burn. superficial burns may be managed with little more than simple pain medication, while major burns may require prolonged treatment in specialized burn centers. cooling with tap water may help pain and decrease damage; however, prolonged cooling may result in low body temperature. partial-thickness burns may require cleaning with soap and water, followed by dressings. it is not clear how to manage blisters, but it is probably reasonable to leave them intact if small and drain them if large. full-thickness burns usually require surgical treatments, such as skin grafting. extensive burns often require large amounts of intravenous fluid, due to capillary fluid leakage and tissue swelling. the most common complications of burns involve infection. tetanus toxoid should be given if not up to date. in 2015, fire and heat resulted in 67 million injuries. this resulted in about 2.9 million hospitalizations and 176,000 deaths. among women in much of the world, burns are most commonly related to the use of open cooking fires or unsafe cook stoves. among men, they are more likely a result of unsafe workplace conditions. most deaths due to burns occur in the developing world, particularly in southeast asia. while large burns can be fatal, treatments developed since 1960 have improved outcomes, especially in children and young adults. in the united states, approximately 96% of those admitted to a burn center survive their injuries. the long-term outcome is related to the size of burn and the age of the person affected. signs and symptoms the characteristics of a burn depend upon its depth. superficial burns cause pain lasting two or three days, followed by peeling of the skin over the next few days. individuals with more severe burns may indicate discomfort or complain of feeling pressure rather than pain. full-thickness burns may be entirely insensitive to light touch or puncture. while superficial burns are typically red in color, severe burns may be pink, white or black. burns around the mouth or singed hair inside the nose may indicate that burns to the airways have occurred, but these findings are not definitive. more worrisome signs include: shortness of breath, hoarseness, and stridor or wheezing. itchiness is common during the healing process, occurring in up to 90% of adults and nearly all children. numbness or tingling may persist for a prolonged period of time after an electrical injury. burns may also produce emotional and psychological distress. typelayers involvedappearancetexturesensationhealing timeprognosis and complicationsexample superficial (first-degree)epidermisred without blistersdrypainful5–10 daysheals well. repeated sunburns increase the risk of skin cancer later in life. superficial partial thickness (second-degree)extends into superficial (papillary) dermisredness with clear blister. blanches with pressure.moistvery painful2–3 weekslocal infection (cellulitis) but no scarring typically deep partial thickness (second-degree)extends into deep (reticular) dermisyellow or white. less blanching. may be blistering.fairly drypressure and discomfort3–8 weeksscarring, contractures (may require excision and skin grafting) full thickness (third-degree)extends through entire dermisstiff and white/brown. no blanching.leatherypainlessprolonged (months) and unfinished/incompletescarring, contractures, amputation (early excision recommended) fourth-degreeextends through entire skin, and into underlying fat, muscle and boneblack; charred with eschardrypainlessdoes not heal; requires excisionamputation, significant functional impairment and, in some cases, death. cause burns are caused by a variety of external sources classified as thermal (heat-related), chemical, electrical, and radiation. in the united states, the most common causes of burns are: fire or flame (44%), scalds (33%), hot objects (9%), electricity (4%), and chemicals (3%). most (69%) burn injuries occur at home or at work (9%), and most are accidental, with 2% due to assault by another, and 1–2% resulting from a suicide attempt. these sources can cause inhalation injury to the airway and/or lungs, occurring in about 6%. burn injuries occur more commonly among the poor. smoking and alcoholism are other risk factors. fire-related burns are generally more common in colder climates. specific risk factors in the developing world include cooking with open fires or on the floor as well as developmental disabilities in children and chronic diseases in adults. thermal main article: thermal burn see or edit source data. rate of deaths (per 100,000) due to fire between 1990 and 2017. in the united states, fire and hot liquids are the most common causes of burns. of house fires that result in death, smoking causes 25% and heating devices cause 22%. almost half of injuries are due to efforts to fight a fire. scalding is caused by hot liquids or gases and most commonly occurs from exposure to hot drinks, high temperature tap water in baths or showers, hot cooking oil, or steam. scald injuries are most common in children under the age of five and, in the united states and australia, this population makes up about two-thirds of all burns. contact with hot objects is the cause of about 20–30% of burns in children. generally, scalds are first- or second-degree burns, but third-degree burns may also result, especially with prolonged contact. fireworks are a common cause of burns during holiday seasons in many countries. this is a particular risk for adolescent males. in the united states, for non-fatal burn injuries, white males, aged <6 comprise most cases. thermal burns from grabbing/touching and spilling/splashing were the most common type of burn and mechanism, while the bodily areas most impacted were hands and fingers followed by head/neck. chemical main article: chemical burn chemical burns can be caused by over 25,000 substances, most of which are either a strong base (55%) or a strong acid (26%). most chemical burn deaths are secondary to ingestion. common agents include: sulfuric acid as found in toilet cleaners, sodium hypochlorite as found in bleach, and halogenated hydrocarbons as found in paint remover, among others. hydrofluoric acid can cause particularly deep burns that may not become symptomatic until some time after exposure. formic acid may cause the breakdown of significant numbers of red blood cells. electrical main article: electrical burn electrical burns or injuries are classified as high voltage (greater than or equal to 1000 volts), low voltage (less than 1000 volts), or as flash burns secondary to an electric arc. the most common causes of electrical burns in children are electrical cords (60%) followed by electrical outlets (14%). lightning may also result in electrical burns. risk factors for being struck include involvement in outdoor activities such as mountain climbing, golf and field sports, and working outside. mortality from a lightning strike is about 10%. while electrical injuries primarily result in burns, they may also cause fractures or dislocations secondary to blunt force trauma or muscle contractions. in high voltage injuries, most damage may occur internally and thus the extent of the injury cannot be judged by examination of the skin alone. contact with either low voltage or high voltage may produce cardiac arrhythmias or cardiac arrest. radiation main article: radiation burn radiation burns may be caused by protracted exposure to ultraviolet light (such as from the sun, tanning booths or arc welding) or from ionizing radiation (such as from radiation therapy, x-rays or radioactive fallout). sun exposure is the most common cause of radiation burns and the most common cause of superficial burns overall. there is significant variation in how easily people sunburn based on their skin type. skin effects from ionizing radiation depend on the amount of exposure to the area, with hair loss seen after 3 gy, redness seen after 10 gy, wet skin peeling after 20 gy, and necrosis after 30 gy. redness, if it occurs, may not appear until some time after exposure. radiation burns are treated the same as other burns. microwave burns occur via thermal heating caused by the microwaves. while exposures as short as two seconds may cause injury, overall this is an uncommon occurrence. non-accidental in those hospitalized from scalds or fire burns, 3–10% are from assault. reasons include: child abuse, personal disputes, spousal abuse, elder abuse, and business disputes. an immersion injury or immersion scald may indicate child abuse. it is created when an extremity, or sometimes the buttocks are held under the surface of hot water. it typically produces a sharp upper border and is often symmetrical, known as "sock burns", "glove burns", or "zebra stripes" - where folds have prevented certain areas from burning. deliberate cigarette burns most often found on the face, or the back of the hands and feet. other high-risk signs of potential abuse include: circumferential burns, the absence of splash marks, a burn of uniform depth, and association with other signs of neglect or abuse. bride burning, a form of domestic violence, occurs in some cultures, such as india where women have been burned in revenge for what the husband or his family consider an inadequate dowry. in pakistan, acid burns represent 13% of intentional burns, and are frequently related to domestic violence. self-immolation (setting oneself on fire) is also used as a form of protest in various parts of the world. pathophysiology three degrees of burns at temperatures greater than 44 °c (111 °f), proteins begin losing their three-dimensional shape and start breaking down. this results in cell and tissue damage. many of the direct health effects of a burn are caused by failure of the skin to perform its normal functions, which include: protection from bacteria, skin sensation, body temperature regulation, and prevention of evaporation of the body's water. disruption of these functions can lead to infection, loss of skin sensation, hypothermia, and hypovolemic shock via dehydration (ie. water in the body evaporated away). disruption of cell membranes causes cells to lose potassium to the spaces outside the cell and to take up water and sodium. in large burns (over 30% of the total body surface area), there is a significant inflammatory response. this results in increased leakage of fluid from the capillaries, and subsequent tissue edema. this causes overall blood volume loss, with the remaining blood suffering significant plasma loss, making the blood more concentrated. poor blood flow to organs like the kidneys and gastrointestinal tract may result in kidney failure and stomach ulcers. increased levels of catecholamines and cortisol can cause a hypermetabolic state that can last for years. this is associated with increased cardiac output, metabolism, a fast heart rate, and poor immune function. diagnosis burns can be classified by depth, mechanism of injury, extent, and associated injuries. the most commonly used classification is based on the depth of injury. the depth of a burn is usually determined via examination, although a biopsy may also be used. it may be difficult to accurately determine the depth of a