| Classification | Tissue Damage | Appearance | Pain | Clinical Course |
|---|---|---|---|---|
| Superficial (first degree) | Epidermis | Mild to fiery red erythema; no blisters | Very painful | Ordinarily heals in 37 days |
| Partial thickness; superficial or deep (second degree) | Epidermis and dermis |
|
| Healing takes 1018 days; if infection develops in deep burn, it converts to full-thickness burn
|
| Full thickness (third degree) | All layers of skin and subcutaneous tissue | Charred, leathery or pale and dry | Usually absent | Heals only with grafting or scarring |
| *Fourth degree | All layers of skin, subcutaneous tissue, muscle, and bone | Black | Same as full thickness | Same as full thickness |
* Used in some classification systems. May require several days after a severe burn to determine fourth degree.