A chemical burn is tissue damage caused by contact with corrosive substances, such as strong acids, alkalis (bases), or oxidizing agents. Unlike thermal burns, chemical injuries involve a direct reaction with the skin and underlying tissues. Severity depends on the chemical’s concentration, duration of exposure, and specific properties. The resulting appearance of the burn provides clues about the extent of the damage and the type of substance involved.
Initial Symptoms and General Appearance
The immediate signs of a chemical burn indicate injury, even before the full extent of the damage is visible. Pain is a common initial symptom, though it can be delayed or absent in deeper injuries where nerve endings have been destroyed. The affected area often shows redness, irritation, and localized swelling.
A change in skin texture is a distinctive feature of some chemical injuries. Exposure to an alkali, such as drain cleaner, might cause the skin to feel slippery or soapy. Conversely, contact with a strong acid can make the skin feel hard or waxy due to rapid tissue structure change. Numbness or tingling in the contact area signals damage to the nerve endings beneath the surface.
Visual Identification by Burn Severity
Chemical burns are classified by the depth of tissue penetration, similar to thermal burns. First-degree burns are the most superficial injuries, involving only the outermost layer of skin (the epidermis). These areas look red, are dry, and will turn white temporarily when gentle pressure is applied (blanching).
Partial thickness (second-degree) injuries extend deeper, affecting both the epidermis and the dermis. These burns are characterized by the formation of blisters and a mottled, intensely red or pale pink appearance. The wound surface may weep fluid, and the area remains sensitive and painful.
Full thickness (third-degree) injuries are the most severe, destroying the full depth of the skin and often reaching underlying fat, muscle, or bone. These injuries present a change in texture, appearing leathery, waxy, or rigid. The color ranges from white or deep brown to charred black, and the area is painless because the nerve endings have been destroyed.
Differences in Appearance Based on Chemical Type
The type of chemical agent fundamentally changes the burn’s appearance by altering the mechanism of tissue destruction. Acidic substances cause coagulation necrosis, where proteins in the skin are denatured and clump together. This reaction creates a dry, thick, protective crust, called an eschar, which limits the acid’s ability to penetrate deeper into the tissue.
Acid burns often result in a white, yellowish, or dark brown crust on the skin surface. Sulfuric acid is an exception, tending to produce a distinct black eschar. Conversely, alkaline substances, such as lye or cement, cause a more destructive process called liquefaction necrosis.
Liquefaction necrosis breaks down fatty tissues and proteins through saponification, allowing the chemical to penetrate tissue layers deeper and faster. Alkali burns may appear gray, slimy, or soapy, and the damage can progress for hours or days after contact. Alkali burns are considered more damaging than acid burns because the lack of a protective barrier allows for continuous, deep-tissue injury.
Immediate Emergency Steps
Responding quickly to a chemical burn minimizes the extent of tissue damage. The first step is to remove the chemical from the skin to stop the reaction. If the substance is a dry powder, such as lime or certain fertilizers, it must be gently brushed off before any water is applied, as water can activate or intensify the corrosive effect.
Once solid chemicals are removed, or for liquid chemicals, the area should be flushed immediately with cool running water for at least 20 minutes. While flushing, remove all contaminated clothing, jewelry, and accessories from the affected area. Do not attempt to use another chemical to neutralize the burn, as this can generate heat and worsen the injury.
After flushing, or if the burn involves the eyes or a large area, professional medical help should be sought immediately. Even if the burn appears minor, a medical assessment is necessary because the full extent of chemical damage may not be immediately apparent. Take the chemical container or label to the medical facility to assist doctors in determining the correct treatment.