Burns on the skin of the legs: chemical, thermal and solar - degrees and treatment

Burns to the skin of the legs are common and include three main causes: thermal factors (fire, hot surfaces, boiling water), chemical agents (acids, alkalis, organic solvents, and special substances such as hydrofluoric acid), and ultraviolet radiation from the sun, which causes sunburn. The severity of the injury depends on the depth of damage to the skin layers, the body surface area, age, underlying medical conditions, and the speed of first aid. Burns to the lower extremities pose a risk of swelling, pain, infection, contractures, and gait disturbances. [1]

The key to reducing severity is proper first aid: rapid cooling of the injury with cool running water for 20 minutes in the first 3 hours for thermal or sunburn, safe decontamination for chemical burns, and early assessment for referral to a specialized burn center. These steps reduce the depth of injury, decrease the likelihood of surgery, and improve long-term outcomes. [2]

Chemical burns have some key exceptions: one should not attempt to "neutralize" an acid with an alkali, or vice versa, as this will increase thermal damage. Special protocols exist for certain substances. Hydrofluoric acid is particularly dangerous, as it can cause severe systemic calcium metabolism disorders; phenol requires treatment with polyethylene glycol. [3]

Even with superficial leg burns, it is important to assess tetanus vaccination status and administer prophylaxis if necessary. For deep burns, large areas, and vulnerable anatomical areas, consultation with a burn specialist is recommended, based on the American Burn Association criteria. [4]

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision, thermal and chemical burns of the lower extremities are coded under the "Burns and Corrosions" section. Code T24 is used for the thigh and shin, and T25 for the ankle and foot. Sunburn is coded under section L55, grading by severity. Additional codes T31-T32 are used to assess area. [5]

The International Classification of Diseases, Eleventh Revision, uses clarifying entries for localization and etiology: "burn of thigh or lower leg, excluding ankle and foot," "burn of ankle or foot," "acute injury of skin due to contact with a corrosive substance," "sunburn." Extension codes for depth, side, and circumstances are also used. [6]

Table 1. Frequently used codes

Classification	Code	Name
ICD-10	T24	Burn and corrosion of the thigh and lower limb, except for the ankle and foot
ICD-10	T25	Burn and corrosion of the ankle and foot
ICD-10	L55.0 L55.1 L55.2 L55.9	Sunburn: first degree, second degree, third degree, unspecified
ICD-10	T31-T32	Percentage of body surface affected
ICD-11	ND96 ND97	Burn of the thigh or lower leg; burn of the ankle or foot
ICD-11	ND99	Acute skin injury from a corrosive substance
ICD-11	EJ40	Sunburn
[7]

Epidemiology

According to the World Health Organization, burns cause approximately 180,000 deaths annually, primarily in low- and middle-income countries. Non-fatal burns result in prolonged hospitalization, disabling scars, and social stigma, accounting for a significant proportion of lost years of good life. [8]

Global estimates of the burn burden are refined in the Global Burden of Disease studies. Publications for 2019–2021 indicate a multi-million prevalence of burn injuries, with regional variations and a gradual decline in age-standardized rates, while absolute numbers remain high due to population growth. [9]

According to the American Burn Association, tens of thousands of burn hospitalizations, including those with multiple injuries, are recorded annually at specialized centers. These reports illustrate the importance of organized referral pathways and standardized first aid. [10]

Sunburn remains one of the most common forms of skin damage worldwide, particularly in summer and in southern regions. It increases the risk of photoaging and skin neoplasia with repeated episodes, requiring consistent exposure prevention and proper sun protection habits. [11]

Reasons

Thermal burns of the skin of the feet are caused by flames, hot liquids, steam, and contact with hot surfaces and objects. Common household scenarios include spilling boiling water, falling onto a hot surface, contact with hot coals and smoldering objects, and splashes of oil while frying. [12]

Chemical burns occur when skin comes into contact with acids, alkalis, oxidizing agents, organic solvents, and certain salts. Fluoride-containing agents, such as hydrofluoric acid, are particularly dangerous, as they rapidly penetrate tissue, causing necrosis and severe hypocalcemia. Phenol can also cause deep damage and systemic toxicity. [13]

Sunburn is the result of excessive ultraviolet exposure without adequate protection. The risk increases when near water, at high altitudes, and in open areas during midday hours, as well as when taking photosensitizing medications and using cosmetics containing acids. [14]

Finally, mixed mechanisms occur in injuries at work, at home, and in emergency situations, when chemical contamination is added to the thermal factor, which requires priority decontamination and subsequent cooling. [15]

Risk factors

Risk factors for severe progression include age extremes, concomitant diabetes, vascular disease of the legs, immunodeficiency, smoking, and obesity, as well as delays in initiating proper first aid. These factors increase the chances of deep damage, slow healing, and complications. [16]

The risk of chemical burns increases with work performed without personal protective equipment, unlabeled storage of reagents, use of inappropriate neutralizing agents, and the absence of emergency decontamination protocols. The presence of calcium gluconate and polyethylene glycol gels in the laboratory significantly improves the outcome of exposure to hydrofluoric acid and phenol. [17]

Sunburn is associated with fair skin, adolescence and young adulthood, exposure to water and snow, active recreation during periods of high sun exposure, and recent peeling or phototherapy. Regular and proper sun protection significantly reduces the frequency of episodes. [18]

Smoke inhalation, concomitant injuries, and delayed hospitalization are also risk factors for adverse outcomes in extensive burns. Evaluation of the indications for referral to a specialized center is based on standardized criteria. [19]

Pathogenesis

Thermal burns cause coagulative necrosis and pericapillary vascular damage in the stress zone surrounding the central coagulation zone. Depth is determined by temperature and exposure time, as well as the rate of heat removal; therefore, rapid cooling reduces the transition from superficial to deep damage. [20]

Chemical burns are caused by coagulation or liquefaction necrosis. Alkalis provide deeper penetration by saponifying fats and breaking down proteins; some agents (hydrofluoric acid) also cause life-threatening systemic electrolyte disturbances. [21]

In sunburn, ultraviolet radiation triggers a cascade of inflammatory mediators, DNA damage, and keratinocyte apoptosis, which clinically manifests as erythema, pain, and subsequent scaling. Repeated episodes lead to cumulative damage to dermal structures. [22]

In deep circular burns of the extremities, the resulting dense crust can compress vessels and nerves, threatening ischemia and compartment syndrome, which requires urgent assessment of perfusion and, if necessary, performing an escharotomy. [23]

Symptoms

Superficial burns present with painful erythema, swelling, and increased sensitivity. With superficial partial burns, moist blisters appear, pain persists, and capillary refill is preserved. These forms usually heal spontaneously without scarring. [24]

With deep partial injuries, blisters may be large, the surface may be pale or marbled, sensitivity is reduced, and the capillary reflex is weak. The risk of infection and scarring is higher, and healing times are longer. [25]

Complete skin damage appears dry, white, or charred, with no pain due to the destruction of nerve endings. Spontaneous healing is virtually nonexistent, requiring surgical intervention and skin grafting. [26]

Sunburns cause erythema, burning, swelling, and sometimes blistering and systemic discomfort. Symptomatic therapy and skin care are often all that's needed, but if blisters occur over a large area of the legs, medical evaluation is indicated. [27]

Classification, forms and stages

The classic clinical classification by depth includes superficial epidermal burn, superficial partial dermal injury, deep partial dermal injury, and complete skin injury. Each grade has different perfusion characteristics, sensitivity, and expected healing time. [28]

In adults, the lesion area is often assessed using the "rule of nines," while in children, the Lund and Browder diagram is used, which takes into account age-related body proportions and provides a more accurate assessment. For statistics and communication with the emergency department, body surface area percentages are used. [29]

Chemical burns are classified by agent and depth, taking into account toxicokinetics; specific treatment algorithms are provided for certain substances. Sunburns are graded by degree and area. [30]

Table 2. Classification by depth and estimated healing times

Level	Skin layers	Clinic	Estimated healing
Superficial epidermal	Epidermis	Erythema, pain, dry skin	Up to 7 days, no scar
Superficial partial	Epidermis and superficial dermis	Wet blisters, severe pain, rapid capillary reflex	7-14 days, minimal traces
Deep partial	Deep dermis	Pale or marbled surface, decreased sensitivity	14-28 days, risk of scarring
Full	The entire thickness of the skin	Dry white or charred tissue, no pain	It doesn't heal on its own and requires surgery.
[31]

Table 3. The "Rule of Nines" for Adults and Foot Guidelines

Region	Percentage of body surface area
The entire lower limb	18%
Anterior surface of the leg	9%
Back of the leg	9%
Foot	Part of the lower limb
[32]

Complications and consequences

Infectious complications include cellular infections, abscesses, and sepsis. Prophylactic administration of systemic antibiotics to uncomplicated burns does not improve outcomes and is not recommended because it increases the risk of resistance; antibacterial therapy is indicated for signs of infection. [33]

Functional consequences in the legs include contractures, hypertrophic and keloid scars, chronic pain, gait disturbances, and foot loading. Early mobilization, physical therapy, and proper bandaging reduce the risk. [34]

In deep, circular lesions, ischemia of the limb segment may occur due to compression, requiring urgent perfusion assessment and, if necessary, escharotomy. Delayed decompression carries the risk of irreversible damage. [35]

In chemical burns, systemic effects pose a particular threat: with hydrofluoric acid, hypocalcemia and arrhythmia; with phenol, systemic toxicity. Electrolyte and heart rate monitoring are necessary as indicated. [36]

When to see a doctor

Immediate medical attention is needed for any deep burn area, blistering burns over a significant portion of the leg, circumferential burns, signs of impaired blood flow to the foot, pain that is not controlled by available means, and signs of infection. [37]

Seeking medical attention is essential for chemical burns of any depth, exposure to an unknown substance, contact with hydrofluoric acid or phenol, and eye damage from chemical splashes. [38]

Evaluation should be sought for sunburn with significant blisters, severe weakness, dehydration, or risk factors for severe outcome, including older age, chronic illness, and immunosuppression.[39]

Indications for referral to a specialized burn center include depth of complete injury of any area, damage to large joints of the leg, superficial burns over 10% of the body surface, chemical and inhalation injuries, and combined injuries. [40]

Diagnostics

1. Initial assessment and triage. Assess vital signs, remove jewelry from the foot, assess foot perfusion, sensation, and pain. Determine the approximate depth and area based on clinical examination and landmarks in the tables. [41]
2. Determining the area and depth. For adults, use the "rule of nines"; for children, use the Lund and Browder diagram. Photographic documentation, if possible. If in doubt, seek early consultation with a burn specialist. [42]
3. Laboratory tests as indicated. Complete blood count, C-reactive protein, electrolytes. For chemical burns - targeted tests: for hydrofluoric acid - calcium, magnesium, potassium, ECG; for phenol - assessment of systemic toxicity. [43]
4. Assess for ischemia and compartment syndrome. Check capillary refill, temperature, dorsalis pedis and posterior tibial artery pulses, and Doppler ultrasound if necessary; consider escharotomy if signs of compression are present. [44]
5. Microbiological diagnostics. Cultures are taken when signs of infection are present or when treatment is ineffective; prophylactic cultures are not required in the absence of symptoms. [45]
6. Assess vaccination status. Check tetanus vaccination schedule and determine indications for the administration of toxoid and immunoglobulin depending on the nature of the wound. [46]

Differential diagnosis

Burns should be differentiated from contact dermatitis, cold injury, necrotizing infections, ulcers due to circulatory impairment, and pemphigus and bullous impetigo, which can mimic blisters. A proper history and exposure assessment are key guidelines. [47]

In case of sunburn, it is important to exclude phototoxic and photoallergic reactions to medications and cosmetics, which can cause a more prolonged and marbled lesion with different dynamics. [48]

Chemical burns are differentiated from thermal burns by circumstances, odor, tissue characteristics, and often by continued damage after exposure. The presence of a specific agent dictates special measures. [49]

In deep and circular lesions of the legs, ischemia due to compression is differentiated from vascular thrombosis and compartment syndrome of other causes. [50]

Treatment

First aid for thermal and sunburns. Immediately begin cooling the affected area of the leg with cool running water for 20 minutes, preferably within the first 3 hours after the injury. Do not apply ice, fats, or ointments until cooling is complete. After cooling, cover the burn with a clean, non-adherent bandage or film, and elevate the limb to reduce swelling. These measures reduce the depth and reduce the likelihood of surgery. [51]

First aid for chemical burns: Immediately remove contaminated clothing and shoes. For powdered substances, carefully remove the dry material from the skin, then rinse thoroughly with water. Do not attempt household "neutralization." For phenol, it is preferable to repeatedly wipe the affected area with polyethylene glycol, reapplying it until the odor disappears; if not, rinse with water for a long time. For hydrofluoric acid, after copious rinsing, apply calcium gluconate gel as soon as possible and assess electrolytes and an ECG. [52]

Pain relief and care. Nonsteroidal anti-inflammatory drugs are used unless contraindicated; cold compresses and moisturizers containing aloe or soy are helpful for sunburn. Local anesthetics containing benzocaine are not recommended due to the risk of irritation and allergy. Topical and systemic glucocorticoids have not been shown to be beneficial for sunburn. [53]

Selection of dressings and topical agents. For superficial and partial-thickness burns of the legs, atraumatic silicone mesh, self-adhesive foam dressings, hydrofibers, and modern ionic silver-containing coatings are used as indicated. The use of silver sulfadiazine as a "default" treatment is being reconsidered: reviews indicate slower healing compared to modern dressings. The choice depends on exudation, comfort, availability, and experience. [54]

Infection prevention. Routine administration of systemic antibiotics for uncomplicated burns is not indicated. Antibiotics are warranted for clinical signs of infection, cellulitis, or in patients with special risks, as determined by the physician. Dressing hygiene and pain control are basic measures. [55]

Instrumental wound treatment. Gentle debridement, opening of large tense blisters while preserving the dressing as a biological dressing, and gentle debridement. In cases of severe necrosis, more active debridement is indicated. Elastic bandaging and positioning are essential to prevent swelling and contractures. [56]

Enzymatic debridement with bromelain. For deep burns, selective enzymatic debridement has been proven effective, accelerating debridement and reducing the need for surgical excisions and autografts, without compromising scar closure time or quality. This method is not intended for chemical burns or certain anatomical areas; it requires selection and preparation. [57]

Infusion therapy for large areas. For lesions covering a significant body surface area, initial crystalloid replacement is calculated using generally accepted formulas, followed by titration based on diuresis and clinical findings. Caution is required in the elderly and in those with concomitant cardiac pathology, and for isolated, small burns of the legs, systemic infusion is usually unnecessary. [58]

Tetanus prophylaxis. All burn patients should have their vaccination status assessed and receive prophylaxis according to current recommendations, including administration of toxoid and, for certain wounds, immunoglobulin. Antibiotics do not prevent tetanus and are not prescribed for this purpose. [59]

Early rehabilitation. Leg positioning, elevation, active and passive movements within pain-free limits, and compression garments for those with a tendency toward hypertrophic scarring. The goal is to maintain range of motion and prevent contractures, which is critical for the ankle and foot. [60]

Table 4. First aid: what to do and what to avoid

Situation	Do	Avoid
Thermal burn	20 minutes of cooling with running water, sterile bandage, elevate the limb	Ice, fats, homemade ointments
Chemical burn	Remove contaminated clothing, rinse with water for a long time; phenol - polyethylene glycol; hydrofluoric acid - calcium gluconate gel	"Neutralization" of acids and alkalis, delayed decontamination
Sunburn	Cooling compresses, moisturizers, oral nonsteroidal anti-inflammatory drugs for pain	Benzocaine, alcohol-containing lotions, non-systemic glucocorticoids
[61]

Table 5. Dressings and topical solutions for superficial burns of the legs (selection by objectives)

Task	Examples of solutions	Comments
Atraumatic and comfortable	Silicone mesh, foam dressings	Reduces pain during dressing changes
Exudate control	Hydrofibers, modern bandages with silver	Use as directed, change as needed
Antimicrobial activity	Ionic silver in modern dressings	Consider if there is a risk of infection
Outdated approaches	Silver sulfadiazine "by default"	May slow down epithelialization compared to modern coatings
[62]

Prevention

Household prevention includes caution when preparing food, wearing sturdy footwear and clothing when handling hot liquids, securing bath mats, and restricting children's access to heat and hot water. In the workplace, training, personal protective equipment, and emergency decontamination protocols are essential. [63]

For chemical hazards, labeled storage of reagents, availability of safety showers, polyethylene glycol and calcium gluconate gel kits where phenol and hydrofluoric acid are handled, and regular staff training are critical. [64]

Sun prevention includes limiting exposure to direct sunlight during midday hours, wearing long-legged clothing and wide-brimmed hats, broad-spectrum sunscreens, and reapplication, especially near water and when sweating.[65]

Tetanus vaccination according to the schedule and monitoring of revaccination schedules remain mandatory for all those who may receive skin injuries, including burns. [66]

Forecast

The prognosis for superficial burns of the legs is favorable, with full recovery usually occurring within 1-2 weeks without scarring with proper care. Prompt initiation of proper first aid improves outcomes. [67]

In deep and extensive injuries, the outcome depends on the body surface area, depth, and presence of inhalation injury; modern techniques, including selective enzyme debridement, reduce the need for surgery and blood loss. [68]

Functional outcomes are improved with early rehabilitation, edema control, and contracture prevention. Timely referral to a burn center reduces complications and disability. [69]

Repeated sunburns increase long-term risks to the skin, so prevention is a key part of long-term prognosis. [70]

FAQ

Can ice or sour cream be applied to a thermal burn?
No. Ice increases vascular spasm and can worsen the damage, while fats delay heat transfer and contaminate the wound. It's best to cool the burn for 20 minutes with running water, then apply a non-stick bandage and elevate the limb. [71]

When can irrigation be stopped after a chemical burn?
At least until the pain stops and the contamination is removed; in the case of phenol, repeat treatments with polyethylene glycol until the odor disappears; in the case of hydrofluoric acid, topical calcium gluconate gel and medical supervision are required after irrigation. [72]

Are antibiotics necessary "just in case"?
No, prophylactic use of systemic antibiotics for uncomplicated burns does not improve outcomes and is not recommended. Antibiotics are prescribed for signs of infection at the discretion of a physician. [73]

What should you do if you have sunburned feet with blisters?
Cool, moisturize, control pain with oral medications, do not break the blisters yourself, apply a non-traumatic bandage, and consult a doctor if the area is large or there is significant discomfort. [74]

Should vaccinations be checked for any burn?
Yes, tetanus vaccination status is mandatory. For certain types of wounds, toxoid and immunoglobulin may be required. Antibiotics are not a substitute for tetanus prophylaxis. [75]