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Which layers of skin are damaged by a first-degree burn?

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Cross-section diagram of human skin showing burn depth by degree, with arrows indicating that first-degree burns affect only the epidermis, second-degree burns reach the dermis, third-degree burns extend into subcutaneous tissue, and fourth-degree burns penetrate to muscle. — burn This diagram shows how burn injuries are classified by severity. First-degree burns damage the outer skin, known as the epidermis. First-degree burns are the least severe form of burn injury. Second-degree burns damage the outer skin and some of the underlying skin, known as the dermis, which also includes some connective tissue. Third-degree burns damage all the layers of skin, including subcutaneous tissue. Fourth-degree burns, which are the most severe, destroy every layer of skin and also damage muscle, tendons, and bones.

A first-degree burn is a mild injury that affects only the epidermis, which is the outermost layer of the skin.1

These injuries are characterized by redness, pain, and heat, but they do not exhibit blistering or charring of the tissues. A common example of a first-degree burn is a moderate sunburn.21