Burns can vary in severity from first-degree to third-degree burns. While first-degree burns are mild and typically affect only the outermost layer of skin, second-degree and third-degree burns tend to be significantly more severe. Second-degree burns cause damage to the skin layers below the top layer of skin, resulting in blisters and redness, whereas third-degree burns penetrate all layers of the skin. The most severe burns may lead to damage to internal organs and bones, as well as a heightened risk of infection.