An eschar is a type of necrotic tissue. Necrosis is the medical term for body tissue death. An eschar is essentially a collection of this dead tissue that becomes dry, hard, and leathery, and it is firmly attached to the surrounding healthy skin and the underlying wound bed. It is most commonly seen in the context of full-thickness burns and advanced pressure ulcers (bedsores).

To understand the difference between a simple scab and an eschar, it is helpful to use an analogy.

• Think of healthy skin as a lush, green lawn with a deep, rich layer of topsoil underneath that provides water and nutrients.
• A simple scab, like one that forms over a scraped knee, is like a temporary patch of dried grass and dirt placed over the surface while new grass grows easily underneath.
• An eschar is completely different. It is as if a severe fire has swept through the lawn, burning not only the grass but also scorching the topsoil and destroying all the roots and seeds deep beneath it. The eschar is the resulting thick, black, leathery crust of burnt earth and dead roots. It is a sign of a much deeper injury. Nothing can grow underneath it, and this layer of dead material can prevent healing and create a dangerous environment where bacteria can thrive.

In my experience, an eschar is typically recognized as a dry, dark, and leathery scab that forms over a wound or burn site. It signals that tissue has become necrotic.

An eschar forms due to any process that causes coagulation necrosis of the skin and underlying soft tissues. This means that an injury has been so severe that it has completely cut off the blood supply to that area of tissue. Without blood flow to provide oxygen and nutrients, the cells die, but they initially maintain their structural shape, becoming dry, firm, and leathery.

The most common conditions that lead to the formation of an eschar include:

• Full-Thickness Burns: A third-degree or fourth-degree burn, caused by thermal heat, electricity, or chemicals, is a classic cause. The intense energy from the burn destroys the skin, its blood vessels, and the underlying fatty tissue, creating a thick, inelastic eschar.
• Pressure Ulcers (Bedsores): These are injuries to the skin and underlying tissue that result from prolonged, uninterrupted pressure on a specific part of the body. This pressure, especially over a bony prominence like the sacrum (tailbone), hips, or heels, can cut off blood flow to the skin, leading to tissue death and the formation of an eschar in advanced-stage pressure ulcers.
• Gangrene: The death of body tissue due to a severe lack of blood flow (ischemia) or a serious bacterial infection.
• Vascular Ulcers: In individuals with severe peripheral artery disease or advanced venous insufficiency, the poor circulation can lead to the formation of chronic ulcers on the legs and feet that may develop an eschar. Diabetic foot ulcers are a common example.
• Certain Infections: In rare cases, a specific infectious agent can produce toxins that destroy tissue and form a characteristic eschar. The classic example is cutaneous anthrax.
• Other Causes: This can include certain spider bites (like that of the brown recluse spider), or complications of surgical wounds where the blood supply has been compromised.

In my experience, factors like exposure to extreme heat, chemical injuries, or uncontrolled infections can prompt eschar formation, marking a critical stage in the healing process.

A person does not “get” an eschar directly. It is a sign that develops as part of a severe tissue injury. Therefore, the risk factors for developing an eschar are the risk factors for these underlying conditions.

You are at a higher risk of developing a wound with an eschar if you:

• Are immobile or bedridden, which increases the risk of pressure ulcers.
• Suffer a severe, full-thickness burn.
• Have uncontrolled diabetes, which can lead to diabetic foot ulcers and poor circulation.
• Have severe peripheral artery disease.
• Have a severely compromised immune system.

Clinically, I note that patients typically develop eschars following severe burns or infections, this isn’t something acquired independently but rather as a result of underlying injury or pathological processes.

The primary sign of an eschar is its visual appearance within a wound bed.

• Appearance: It is a thick, dry, hard, and leathery plaque of dead tissue.
• Color: It is typically black but can also be dark brown, tan, or grayish.
• Adherence: It is usually firmly attached to the wound bed and the surrounding skin edges.
• Sensation: The eschar itself is insensate, meaning it has no feeling. This is because the nerve endings within that piece of tissue have been destroyed along with the other cells.

Signs of an Associated Infection

A major danger of an eschar is that it can act as a mask, trapping bacteria and hiding an underlying infection. It is crucial for patients and caregivers to watch for the signs of infection in the skin around the eschar. You should seek immediate medical attention if you notice any of the following:

• Increased pain, redness, or swelling at the edges of the eschar.
• A foul-smelling drainage or pus leaking from underneath the edges of the eschar.
• The eschar itself becomes “boggy,” soft, wet, or loose.
• The development of a fever, chills, or a general feeling of being unwell. These can be signs that the infection is becoming systemic.

Clinically, I assess eschar by its characteristic appearance, a dry, black, or brown, firm scab and by noting any signs of infection or impaired healing in the surrounding tissue.

The diagnosis of an eschar is made by visual inspection during a wound assessment by a doctor, nurse, or a wound care specialist. The characteristic appearance of the black, leathery, necrotic tissue within a wound is diagnostic.

The most important part of the clinical assessment is not just identifying the eschar, but determining if it is stable or unstable. This assessment guides the entire treatment plan.

• Stable Eschar: A stable eschar is dry, hard, intact (with no cracks or openings), and firmly adherent to the wound edges, with no signs of redness, drainage, or infection in the surrounding tissue. A classic example is a dry, hard, black cap on an uninjured heel.
• Unstable Eschar: An unstable eschar is one that shows any signs of infection. It may be wet, draining, loose at the edges, boggy or soft to the touch, or surrounded by redness and swelling. An eschar on the sacrum or ischium (the “sit bones”) is almost always considered unstable due to the high risk of contamination with urine or feces.

In my experience, additional imaging or laboratory tests may be warranted if there is a concern for underlying infection or if the extent of tissue damage isn’t immediately apparent on a physical exam.

The treatment of a wound with an eschar is a complex medical decision that depends entirely on whether the eschar is stable or unstable, its location on the body, and the patient’s overall health and goals of care. You should never try to pick at or remove an eschar yourself.

Treatment of Stable Eschar

It may seem counterintuitive, but the standard medical practice for a stable, dry, and intact eschar, particularly on a heel, is often to leave it alone.

• In this situation, the hard eschar acts as the body’s own “natural biological dressing” or a protective cap. It seals the wound off from the outside environment and prevents bacteria from entering.
• The treatment principle is “if it’s dry, don’t make it wet.” The area is kept clean and dry, and pressure is kept off the area completely. The eschar is monitored closely, and the body is allowed to slowly separate it over time through a natural process called autolysis.

Treatment of Unstable Eschar: Debridement 

If an eschar is unstable, draining, or if there are any signs of infection, it must be removed.

• The medical removal of dead, damaged, or infected tissue is called debridement.
• Debridement is necessary to expose the healthy, living tissue underneath, to allow any underlying collection of pus to drain, and to enable the wound to begin the healing process.
• There are several methods of debridement:
  • Surgical or Sharp Debridement: This is the fastest and most common method. A surgeon or a trained wound care specialist uses a sterile scalpel, scissors, and forceps to physically cut away the dead eschar tissue.
  • Enzymatic Debridement: This involves applying a prescription ointment or cream that contains special enzymes. These enzymes work to slowly dissolve and break down the necrotic tissue.
  • Autolytic Debridement: This method uses special moisture-retentive dressings that trap the body’s own natural enzymes against the wound bed to slowly liquefy and separate the eschar.

Burn Escharotomy

In the specific case of a full-thickness burn that goes all the way around a limb or the chest, the tight, inelastic eschar can act like a tourniquet, cutting off circulation or preventing breathing. In this emergency situation, a surgeon will perform an escharotomy, which involves making long incisions through the eschar to relieve the pressure.

Clinically, I emphasize that management must be tailored to the patient: while some eschars may be left intact as a natural barrier, others require removal if they are impeding wound healing or harboring bacteria.

An eschar is a thick, leathery plaque of dead tissue that forms over a deep, full-thickness wound, most commonly a severe burn or an advanced pressure ulcer. It is a clear sign of a significant injury and should not be confused with a simple scab. While its black and lifeless appearance can be alarming, the management of an eschar is a nuanced clinical decision. A dry, stable eschar is often left in place to act as a natural protective barrier. However, any eschar that shows signs of infection or is draining must be medically removed through a process called debridement to allow the wound to heal. Clinically, I’ve found that a balanced approach to eschar management, watchful waiting versus active debridement leads to better outcomes when it’s adapted to the patient’s overall condition and wound characteristics.

National Pressure Injury Advisory Panel (NPIAP). (n.d.). NPIAP Pressure Injury Stages. Retrieved from https://npiap.com/page/PressureInjuryStages

WoundSource. (2020). The Role of Eschar in the Wound Healing Process. Retrieved from https://www.woundsource.com/blog/role-eschar-wound-healing-process

The Merck Manual Professional Version. (2022). Pressure Injuries. Retrieved from https://www.merckmanuals.com/professional/dermatologic-disorders/pressure-injuries/pressure-injuries