Burns may be classified according to degree or according to skin thickness.
Classification by degree:
- First degree burns: painful, tender, reddened skin without blisters
- Second degree burns: painful, tender, redness skin with blisters
- Third degree burns: painless, charred skin that becomes white or dark
- Fourth degree burns: burns involving muscle, bone or other structures beneath the skin
Classification by thickness:
- Partial-thickness burns:
- Injury limited to the outer layers of the skin
- Full-thickness burns:
- Injury to all the layers of the skin
Burns First Degree
This is a superficial burn that involves only the epidermis. It causes redness to the skin and may cause some minor swelling. Blisters do not result from this degree of burn.
First-degree burns heal without scarring. The most common example of a first-degree burn is sunburn.
Burns Second Degree
Second degree burns extend deeper into the skin, but do not involve all 3 layers. Second-degree burns can be superficial or deep.
Superficial second degree burns involve not only the epidermis, but also a portion of the next skin layer, called the dermis. There is not injury to the deeper layer of the dermis, which contains the sweat glands and the hair follicles. These burns are also called superficial partial-thickness burns.
Second degree burns are usually due to household hazards such as scalding from hot liquids, faulty heating pads or misuse of ignition fluids.
Deep second degree burns, or deep partial-thickness burns, involve the deep layers of the dermis, which contain the sweat glands and the hair follicles. These burns are often difficult to distinguish from full-thickness burns. The skin appears charred and is tender.
Common causes of deep second degree burns include:
- Hot oil
Burns Third Degree
Third degree burns are the most serious form of a burn. They are also called full-thickness burns.
Third degree burns are due to prolonged contact with a very hot object, liquid or gas that damages all 3 layers of skin. Deeper structures, such as muscle, tendon, bone, blood vessels and nerves, may be injured or destroyed.
These burns may cause charring of the skin and loss of sensation due to damaged nerve endings. Infections, scarring and loss of function are common with these deep burns.
Continue to Burns Anatomy
- Allison K, Porter K. Consensus on the prehospital approach to burns patient management. Emerg Med J. 2004 Jan;21(1):112-4. 
- Drago DA. Kitchen scalds and thermal burns in children five years and younger. Pediatrics. 2005 Jan;115(1):10-6. 
- Phillips BJ, Kassir A, Anderson B, Schiller WR. Recreational-outdoor burns: the impact and severity--a retrospective review of 107 patients. Burns. 1998 Sep;24(6):559-61. 
- Smith MA, Munster AM, Spence RJ. Burns of the hand and upper limb--a review. Burns. 1998 Sep;24(6):493-505.