Written By: Kaitlynn Tracy, MD

Edited By: Sean Schnarr, MD and Gregg Chesney, MD


  • Burns are classified as being major, moderate, or minor in severity. The American Burn Association classifies a burn as “minor” if it meets the following criteria:2
    • Partial thickness < 15% BSA in a patient between the ages of 10-50
    • Partial thickness < 10% BSA in a patient younger than 10 or older than 50
    • Full thickness < 2% BSA 
  • In general, a “minor” burn should also be without any following characteristics:2
    • No signs of associated inhalation injury 
    • Not from a chemical or electric burn injury 
    • Not involving the face, hands, perineum, or feet
    • Not crossing any major joints
    • Not circumferential 


  • Every year there are over 500,000 ED visits are due to burn injuries, with 45,000 of those visits requiring hospital admission.7
  • 86% of burn injuries are thermal burns (as opposed to chemical or electric), with 43% resulting from a direct exposure to fire, 34% from scalding liquid, and 9% from a hot object.4
  • Risk factors for sustaining a burn injury include young age (children more frequently come into contact with hot objects), male gender (higher occupational risks and higher rates of alcohol consumption), and a lack of smoke detectors in the home.4
  • Survival rate for all burn injuries is around 97%, which is a notable increase from 75% in the 1960’s.4


  • Thermal burns occur when tissue is exposed to excessive heat, most commonly by direct fire, hot liquid, steam, or a hot surface.4
  • The physiologic response to thermal injury results in three separate zones of injury:7
    • The center of the injury is the “zone of coagulative necrosis” where irreversible tissue necrosis results from the direct thermal exposure.
    • Surrounding that is the “zone of ischemia,” where a large inflammatory response and fluid shift results in reduced blood flow and decreased circulation at the site of injury. 
    • The outermost area on the periphery of the injury is the “zone of hyperemia,” where the inflammatory response causes vasodilation and increased capillary permeability, resulting in tissue edema.

Clinical Presentation:

  • Burn size is the percentage of body surface area (BSA%) involved in the injury. Methods for calculating the BSA% of a thermal injury are listed below:1
    • The most commonly used: Rule of 9’s
    • The most accurate (especially in pediatric patients): Lund and Browder Chart
    • The most accurate for small burns: Rule of Palm 
  • Burn depth is determined by the extent of tissue layers involved in the injury.  The categorizations and their associated clinical presentations are as follows:4,5
    • Superficial: Epidermis involvement only
      • Dry, red, blanches with pressure
      • Does not blister
      • Painful to touch
      • Heals within 3-4 days without scarring 
    • Superficial Partial Thickness: Epidermis + the upper layer of dermis
      • Moist, pink, blanching
      • May blister
      • Hypersensitive to touch
      • Heals in 7-21 days without scarring
    • Deep Partial Thickness: Epidermis + the deeper layer of dermis
      • Dry, red/mottled
      • Do often blister
      • Painful only to pressure
      • Heals in 2-9 weeks with scarring expected
    • Full Thickness: All epidermal layers + subcutaneous tissue or fat
      • Dry, leathery, white
      • Does not blister
      • Painless 
      • Will not heal without skin grafting 
    • Fourth Degree: All epidermal layers + underlying bone, fat, or muscle
      • Painless
      • Will not heal without skin grafting (and occasional amputation)
  • Wounds can continue to increase in depth for up to 72 hours after the injury, so the true depth of the wound may be increased from initial presentation.5
  • Consider the possibility of physical abuse if the burn is in an immersion scald pattern (a burn with well-demarcated lines), there is delayed presentation for evaluation, or the wound is in a specific shape (such as a cigarette butt or the shape or an iron).5


  • Physical exam remains the most common technique for diagnosing burn depth and size.8
  • Additional techniques to aid in the categorization and diagnosis of thermal injuries are actively being studied and include:8 
    • Vital dyes, ultrasound, or tissue biopsy for detecting dead cells or denatured collagen
    • Fluorescein, laser doppler, or thermography to monitor the amount of blood flow in injured tissue
    • MRI to evaluate the extent of hyperemia in injured tissue


  • Patients with joint involvement of a burn may need to start early range of motion exercises, stretching, or occupational therapy to avoid the formation of contractures and permanent disability of the joint.2
  • Hypertrophic scars may form in some patients, which may benefit from pressure garments or topical silicone treatment.6
  • The major systemic processes and metabolic derangements commonly managed in patients with severe thermal injuries rarely occur in patients with minor burns alone.2


  • Cool the injured area by running cold tap water over it for up to 5 minutes.2
    • After 5 minutes there is a risk of vasoconstriction and further tissue damage.
    • Avoid direct contact with ice, which can cause vasoconstriction and increased burn depth.
  • Decontaminate/Cleanse with warm saline irrigation or soapy water.2
    • Do not use skin disinfectants (eg. betadine, iodine), which have been shown to increase inflammation and inhibit the healing process.
  • Debride any loose or dead skin.2
  • Large blisters should be aspirated, while small blisters can be left intact.2
    • This is an area of considerable debate, with varying guidelines between sources.
    • One of the original studies on this topic from 1976 showed evidence that wounds with an intact overlying blister heal faster than those exposed from a ruptured blister, leading to the conclusion that a blister provides a moist environment that benefits healing. There have since been many subsequent studies showing evidence to the contrary.9
  • Apply a topical antimicrobial (eg. Bacitracin, Polymyxin B, or Neomycin) to areas with partial or full thickness burns.2
    • There is no evidence showing a benefit of application to superficial burns.
    • Silver sulfadiazine and silver nitrate have long been a common agent of choice, however recent studies have shown evidence of increased cellular irritation and longer healing times with their use. In accordance, most burn centers have stopped recommending their use. 10
    • There is no indication for prescribing prophylactic systemic antibiotics.
  • Dress the burn with a nonadherent gauze (eg. Xeroform, Telfa, Adaptic), which will cause less pain with removal during dressing changes.2
    • Cover with an outer layer of elastic gauze roll (eg. Kerlix) for additional coverage.
  • Pain can usually be controlled with Acetaminophen, NSAIDS. Also offer second-generation antihistamines (eg. cetirizine) to help alleviate any associated pruritis.2
  • Tetanus immunization should be verified, or a booster vaccine offered.2

Disposition/Next Steps:

  • Patients with minor burns very rarely require hospitalization, and are considered safe for discharge.
  • Patients should be instructed to change their first dressing after 48 hours, and continue dressing changes every 3-5 days until epithelialization of the wound.6
  • Follow up with a primary physician is recommended within 2-3 days of discharge.2
  • Indications for an outpatient referral to a burn center include:2
    • A burn with delayed healing past one week
    • A wound developing signs of infection or tissue necrosis  
  • Indications for emergent consult with or transfer to a burn center include:
    • “Bad Burn:” these burns may require skin grafting or surgical intervention to heal
      • A deep partial or full thickness burn 
      • Burns involving > 10-15% TBSA
    • “Bad Patient:” these burns are at higher rate of superinfection and significant burns lead to a significant cardiovascular demand during the wound healing process
      • A patient less than 5 years of age or greater than 60 
      • A patient with significant comorbidities that increase the healing time or rate of infection (eg. peripheral vascular disease, immunosuppression)
    • “Bad Location:” these burns have a higher risk of significant cosmetic defect or disability if strictures develop
      • A burn located on the face, perineum, feet, or hands


– A partial thickness burn (characterized by the blisters, and background erythema of the epidermis) on the volar aspect of a patient’s forearm. 




Take Home Points:

  1. Thermal injuries are classified by severity as major, moderate, or minor with specific guidelines for categorization. 
  2. Diagnosis of a thermal injury is based on physical exam findings. Thermal injuries are broadly categorized based on the percentage of body surface area that they cover, as well as the depth of tissue injury they cause.
  3. Thermal injuries continue to increase in depth for up to 72 hours after injury, so the final categorization of depth may be different from initial presentation.
  4. Wounds should be cooled with tap water for up to 5 minutes, before being cleaned with soapy warm water. 
  5. Though there is no official recommendation, in general large blisters can be removed, while small blisters can be left intact.
  6. Antimicrobial ointment should be applied to areas with partial or full thickness burned, but is unnecessary in areas with superficial burns.  
  7. Burns should be dressed with a nonadherent gauze, and changed by the patient at home after 48 hours. Subsequent dressing changes can occur every 3-5 days. 
  8. Acetaminophen, NSAIDS, and antihistamines can provide patients with symptomatic relief.
  9. Most minor thermal injuries are safe for discharge home with outpatient follow up after 2-3 days, while some patients will require follow up with specialized care at a burn center. 


  1. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9e Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH. Tintinalli J.E., & Ma O, & Yealy D.M., & Meckler G.D., & Stapczynski J, & Cline D.M., & Thomas S.H.(Eds.),Eds. Judith E. Tintinalli, et al.
  2. Wiktor, Arek, and David Richards. “Treatment of Minor Thermal Burns.” UpToDate, https://www.uptodate.com/contents/treatment-of-minor-thermal-burns?topicRef=350&source=see_link.#H20. 
  3. ​​Swain AH, Azadian BS, Wakeley CJ, Shakespeare PG. “Management of blisters in minor burns.” Br Med J (Clin Res Ed). 1987 Jul 18;295(6591):181. doi: 10.1136/bmj.295.6591.181. PMID: 3115367; PMCID: PMC1247035.
  4. Schaefer TJ, Tannan SC. Thermal Burns. [Updated 2022 May 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430773/
  5. Helman, Anton. “EM Cases – Burn and Inhalation Injuries: Ed Wound Care, Resuscitation and Airway Management.” EmDOCs.net – Emergency Medicine Education, 10 Jan. 2020, http://www.emdocs.net/em-cases-burn-and-inhalation-injuries-ed-wound-care-resuscitation-and-airway-management/. 
  6. Hudspith J, Rayatt S. “First aid and treatment of minor burns.” BMJ. 2004 Jun 19;328(7454):1487-9. doi: 10.1136/bmj.328.7454.1487. PMID: 15205294; PMCID: PMC428524.
  7. Singer, Adam J., et al. “Management of Local Burn Wounds in the Ed.” The American Journal of Emergency Medicine, W.B. Saunders, 30 June 2007, https://www.sciencedirect.com/science/article/abs/pii/S0735675706004499#preview-section-cited-by. 
  8. D. Heimbach, L. Engrav, B. Grube, J. Marvin. “Burn depth: a review.” World J Surg, 16 (1992), pp. 10-15
  9. E.S. Wheeler, T.A. Miller. “The blister and the second degree burn in guinea pigs: the effect of exposure.” Plast Reconstr Surg, 57 (1976), p. 83
  10. (10)J.F. Frazer, J. Bodman, R. Sturgess, J. Faoagali, R.M. Kimble. “An in vivo study of the anti-microbial efficacy of a 1% silver sulfadiazine and 0.2% chlorhexidine digluconate cream, 1% silver sulfadiazine cream and a silver coated dressing.” Burns, 30 (2004), pp. 35-41