Last updated: May 5, 2023

Summarytoggle arrow icon

Burns are injuries to tissue caused by heat, chemicals, electricity, friction, and/or radiation. The two factors that influence the severity of a burn are its depth and the total body surface area (TBSA) involved. The current classification of burns is based on burn depth and recognizes four degrees: first degree (superficial), second degree (superficial partial-thickness and deep partial-thickness), third degree (full-thickness), and fourth degree (deeper-injury burn). The TBSA is calculated using Lund-Browder charts. Massive tissue necrosis, which occurs with severe burns, may result in sepsis, shock, and sequential organ failure (see “SOFA score for details). Patients with severe burns may require intubation, supplemental oxygen, and resuscitation with IV fluids. Various formulas exist to calculate initial fluid requirement, but fluids should be adjusted to maintain clinical stability and appropriate urine output. Blood oxygen, arterial blood gas, electrolyte, and creatinine levels should be monitored closely in patients with third- and fourth-degree burns. In circumferential burns around limbs, peripheral pulses and capillary refill can be used to assess perfusion. Escharotomy should be performed to treat compartment syndrome and prevent acute limb ischemia. First- and second-degree burns can be treated with antiseptic ointment and dressings. Treatment of third- and fourth-degree burns involves debridement of necrotic tissue followed by skin graft or a tissue transfer via flap reconstruction. Burn wounds easily become infected, and large, severe burns are often fatal. The most common causes of death due to burns are shock, sepsis, and respiratory failure.

Etiologytoggle arrow icon

  • Thermal burns (most common) [1]
    • Flame burns: fire
    • Contact burns: hot surfaces
    • Scalding: hot liquids or steam
  • Nonthermal burns [2]
    • Chemical burns
    • Electrical burns
      • Low-voltage sources: electrical cords, outlets in households
      • High-voltage sources: power lines, lightning
    • Radiation burns
      • Electromagnetic waves
        • UV radiation (e.g., from sunlight, phototherapy)
        • X-rays, gamma rays (e.g., from radiotherapy, radiodiagnostic procedures, nuclear accidents)
        • Infrared waves (e.g., from warming lamps), microwaves
      • High-energy particles (e.g., from radiotherapy, nuclear accidents): alpha particles, beta particles, high-energy neutrons
    • Friction burns: skin injury caused by abrasion against a hard surface (esp. at high speeds) and the heat generated by the resulting friction (e.g., from skidding across the street due to a motorcycle accident)

Although most burn injuries are unintentional, intentional injury must always be suspected in vulnerable populations, such as children and older adults.

Classificationtoggle arrow icon

Depth of burns [3]

The measurement of burn depth is based on the skin layer involved.

Overview of burn depth

Degree of burns

Affected tissue layers

Clinical features

Pain Wound blanching on pressure Appearance

1st-degree burn (superficial burn)

  • Yes (localized pain)
  • Yes
  • Rapid refill
  • Healing within 3–6 days
  • No scarring

2nd-degree burn (partial thickness burn)

2a (superficial partial thickness burn)
  • Yes (especially with the movement of air or changes in temperature in the area surrounding the wound)
  • Yes
  • Slow refill
2b (deep partial thickness burn)
  • Yes (pain is typically felt on applying pressure)
  • No
  • Very slow refill
  • Vesicles/bullae: fragile (rupture easily)
  • Mottled coloration of the skin with red and/or white patches
  • Healing takes 3 weeks or longer.
  • Scar formation

3rd-degree burn (full thickness burn)

  • No (perception of deep pressure is intact)
  • No
  • The burn does not heal by itself.

4th-degree burn (deeper injury burn)

  • No (minimal perception of deep pressure)

In deep partial-thickness burns pain may be absent as a result of damage to sensory nerve endings.

Assessment of burn surface area involvement [3]

Total body surface area (TBSA) is the total area of skin involved in an injury (e.g., burn) or disease (e.g., psoriasis). TBSA is calculated using tools such as the Lund-Browder chart and the rule of nines to assess the severity of the skin condition.

  • Rule of nines
    • A clinical tool used to rapidly assess the extent of body surface area affected by burns in adults
    • Divides the adult body's surface into 11 regions (head/neck, 2x anterior trunk, 2x posterior trunk, each arm, 2x each leg), each of which comprises ∼ 9% of the total body surface. or plus 1% for the genital/perineal region
    • The rule of nines does not accurately account for pediatric proportions in children.
  • Lund-Browder chart
    • A set of charts that take into account the different proportions of children and adults (children have proportionally up to 20% larger heads and up to 13% smaller legs) to more precisely estimate the burn surface area involved.
    • Most accurate method for both adults and children
Body surface area estimation
Segment Adult Small child Infant
Head 9% 16% 18%
Trunk 36% (4 x 9%)
Arms 18% (2 x 9%)
Thighs 18% (2 x 9%) 14.5% 13.5%
Lower legs and feet 18% (2 x 9%) 14.5% 13.5%
Genital region 1%
  • Palmar method
    • A method of calculating TBSA using the palm as a unit of measurement to account for different proportions.
    • Least reliable method

1st-degree burns are not included when calculating the total body surface area affected by burns.

Burn severity [4][5]

Burn severity is assessed based on burn depth, TBSA, location, and cause.

Classification of burn severity
Criteria Management
Minor burn
  • Outpatient care
Moderate burn
  • Hospitalization admission
Major burn
  • Burn center

Pathophysiologytoggle arrow icon

Thermal burns

Local effects

  • Local changes at the burn site (Jackson model of the burn wound) [1]
    • Zone of coagulation: a central zone of irreversible, coagulative necrosis
    • Zone of stasis: surrounds the central zone of coagulation and is comprised of damaged but viable tissue with decreased perfusion
    • Zone of hyperemia: surrounds the zone of stasis and is characterized by inflammation and increased blood flow
  • Bacterial colonization of the burn site
  • Eschars: a skin lesion characterized by dried, necrotic skin tissue
    • Can cause constrictive effects
    • Circumferential eschars (burns that fully encircle the chest, neck, abdomen, and/or an extremity) → loss of skin elasticity → impaired blood flow and/or compartment syndrome (caused by an accumulation of fluids) → acute ischemia distal to the eschar
    • Significant eschar on chest or neck → restriction of chest excursion → asphyxia

Inadequate resuscitation and/or wound care may result in irreversible damage to the zone of stasis and increased burn depth.

Systemic effects [6]

Burns involving > 30% of the body surface area and third- or fourth-degree burns are likely to have systemic effects.

Nonthermal burns [7]

Alkali burns cause significantly more tissue damage and have a higher risk of systemic toxicity than acid burns. Local tissue damage from alkalis can continue for up to 2–3 days after exposure.

Diagnosticstoggle arrow icon

Burn severity is based on clinical history and physical examination, but further testing may be necessary to monitor for complications and guide therapy.

Treatmenttoggle arrow icon

Minor burns [12]

Moderate and major burns [13]

Initial management

Immediate management of moderate and major burns should prioritize the ABCDE approach.

Because of the high risk of serious complications, the ATLS and American Burn Association recommend giving only half of the fluid resuscitation volume calculated using the Parkland formula in individuals ≥ 14 years. The volume is administered over 24 hours, with one half given in the first 8 hours and the remaining half over the next 16 hours.

Because fluid resuscitation can worsen laryngeal edema, intubation should be performed as early as possible, if necessary.

Do not use ice or ice water.

Subsequent management [13]

Specific considerations


Chemical burns

  • Immediate, copious irrigation of all areas of exposure with water

Burns from dry lime, phenols, and metals should not be irrigated.

Complicationstoggle arrow icon

We list the most important complications. The selection is not exhaustive.

Inhalation injurytoggle arrow icon

Postburn hypermetabolismtoggle arrow icon


Referencestoggle arrow icon

  1. Hettiaratchy S, Dziewulski P. Pathophysiology and types of burns. BMJ. 2004; 328 (7453): p.1427-1429.doi: 10.1136/bmj.328.7453.1427 . | Open in Read by QxMD
  2. Friedstat J, Brown DA, Levi B. Chemical, Electrical, and Radiation Injuries. Clin Plast Surg. 2017; 44 (3): p.657-669.doi: 10.1016/j.cps.2017.02.021 . | Open in Read by QxMD
  3. Kumar V, Abbas AK, Aster JC. Robbins & Cotran Pathologic Basis of Disease. Elsevier Saunders ; 2014
  4. Walls R, Hockberger R, Gausche-Hill M, Erickson TB, Wilcox SR. Rosen's Emergency Medicine 10th edition- Concepts and Clinical Practice E-Book. Elsevier Health Sciences ; 2022
  5. R. Palao, I. Monge, M. Ruiz, J.P. Barret. Chemical burns: Pathophysiology and treatment. Burns. 2010; 36 (3): p.295-304.doi: 10.1016/j.burns.2009.07.009 . | Open in Read by QxMD
  6. Gentges J, Schieche C. Electrical injuries in the emergency department: an evidence-based review. Emerg Med Pract. 2018; 20 (11): p.1-20.
  7. Julie L. Ryan. Ionizing Radiation: The Good, the Bad, and the Ugly. Journal of Investigative Dermatology. 2012; 132 (3): p.985-993.doi: 10.1038/jid.2011.411 . | Open in Read by QxMD
  8. Ramos CG. Management of fluid and electrolyte disturbances in the burn patient. Annals of Burns and Fire Disasters. 2000; 13 (4).
  9. Hudspith J, Rayatt S. First aid and treatment of minor burns. BMJ. 2004; 328 (7454): p.1487-1489.doi: 10.1136/bmj.328.7454.1487 . | Open in Read by QxMD
  10. Greenhalgh DG. Management of Burns. N Engl J Med. 2019; 380 (24): p.2349-2359.doi: 10.1056/nejmra1807442 . | Open in Read by QxMD
  11. Cartotto R, Greenhalgh DG, Cancio C. Burn State of the Science: Fluid Resuscitation. Journal of Burn Care & Research. 2017; 38 (3): p.e596-e604.doi: 10.1097/bcr.0000000000000541 . | Open in Read by QxMD
  12. Brunicardi F, Andersen D, Billiar T, et al.. Schwartz's Principles of Surgery. McGraw-Hill Education ; 2014
  13. Hettiaratchy S, Papini R. Initial management of a major burn: II—assessment and resuscitation. BMJ. 2004; 329 (7457): p.101-103.doi: 10.1136/bmj.329.7457.101 . | Open in Read by QxMD
  14. Singer AJ, Dagum AB. Current Management of Acute Cutaneous Wounds. N Engl J Med. 2008; 359 (10): p.1037-1046.doi: 10.1056/nejmra0707253 . | Open in Read by QxMD
  15. Advanced Burn Life Support Course. Updated: January 1, 2018. Accessed: May 3, 2023.
  16. Jeschke MG. Postburn Hypermetabolism: : past, present and future. Journal of Burn Care & Research. 2016; 37 (2): p.86-96.doi: 10.1097/bcr.0000000000000265 . | Open in Read by QxMD
  17. Williams FN, Herndon DN, Jeschke MG. The Hypermetabolic Response to Burn Injury and Interventions to Modify this Response. Clin Plast Surg. 2009; 36 (4): p.583-596.doi: 10.1016/j.cps.2009.05.001 . | Open in Read by QxMD

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