An eschar is a thick patch of dead tissue that forms over a wound, typically appearing as a dark brown or black, leathery covering firmly attached to the skin beneath it. Unlike a normal scab, which forms from dried blood and plasma over a superficial cut, an eschar involves deeper layers of skin that have been destroyed and are no longer viable. It can develop after burns, pressure injuries, severe infections, chemical exposure, or any trauma that kills the underlying tissue.
How an Eschar Differs From a Scab
A scab and an eschar can look similar at first glance, but they represent very different stages of tissue damage. A scab is a crust made of dried blood and clotting proteins that sits on top of a shallow wound. It does not contain dead tissue, and it forms as part of the body’s normal healing process for minor injuries. Once the skin underneath regenerates, the scab falls off on its own.
An eschar, by contrast, is composed entirely of devitalized tissue: skin cells that have died and can no longer participate in healing. It can present in several forms. Some eschars are hard and dry, almost like a thick piece of leather stuck to the wound. Others are softer and moist. The key distinction is that the tissue itself is dead, and depending on the situation, it may need to be removed before the wound can heal properly. An eschar can also mask what’s happening underneath it, making it difficult to assess how deep or severe a wound really is.
What Causes an Eschar to Form
Anything that destroys healthy skin can produce an eschar. The most common causes include:
- Burns: thermal, chemical, or electrical burns that penetrate through the full thickness of the skin
- Pressure injuries: prolonged pressure on the skin, particularly over bony areas like the heels, tailbone, or hips, which cuts off blood flow and kills the tissue
- Diabetic foot ulcers: poor circulation and nerve damage in the feet allow wounds to deepen and tissue to die
- Infections: certain bacterial and parasitic infections can cause localized tissue death
- Chemical exposure: acids, alkalis, and certain metallic salts can destroy skin on contact (substances that cause this are called “escharotics”)
- Severe trauma or insect bites: deep tissue damage from injuries or venomous bites
In each of these cases, the common thread is that blood flow to the affected area has been disrupted or the tissue has been directly destroyed, leaving behind a layer of dead cells that the body cannot reabsorb on its own.
Eschars as a Diagnostic Clue
In some infectious diseases, an eschar is actually one of the first visible signs that something is wrong. Scrub typhus, a bacterial infection transmitted by mite bites, often produces a small eschar at the bite site before any other symptoms appear. The CDC notes that these eschars commonly show up in warm, hidden areas of the body like the armpits, under the breasts, or in the groin, though they can appear on the abdomen, back, or limbs. Some patients develop multiple eschars. Because the eschar appears before fever and other systemic symptoms, spotting it early can help clinicians identify the infection and start treatment sooner. Cutaneous anthrax similarly produces a characteristic black eschar that helps distinguish it from other skin conditions.
Why Eschar Complicates Wound Healing
A layer of dead tissue sitting on top of a wound creates problems. It blocks the body’s ability to rebuild healthy skin by acting as a physical barrier between the wound bed and the new cells trying to grow. It also makes it nearly impossible to assess the true depth of a wound. In pressure injury staging, wounds covered by eschar are classified as “unstageable” because clinicians cannot see how much tissue has been lost underneath.
What happens beneath the eschar matters even more. When dead tissue remains in place without proper management, the area underneath can develop liquefaction necrosis, where trapped moisture and bacteria break down the tissue into a pool of infectious fluid. A wound that appeared stable on the surface can suddenly open into a large, deep cavity filled with infected drainage. In patients with weakened immune systems or poor overall health, this hidden infection can progress to sepsis.
Early warning signs that an eschar is hiding trouble include redness spreading around the edges, a sensation of warmth near the wound, fever, or any fluid beginning to seep from beneath the edges. Notably, many patients show redness and localized heat around the eschar before any visible drainage appears, which makes regular monitoring important.
When Eschar Is Removed
Removing dead tissue from a wound is called debridement, and there are several approaches depending on the wound’s severity and the patient’s condition.
Surgical debridement is the most direct method. A clinician uses sharp instruments to cut away the dead tissue, often in combination with other techniques. This is typically used when there are signs of infection beneath the eschar or when the wound needs to heal quickly.
Enzymatic debridement uses a topical preparation that breaks down the proteins holding dead tissue together, allowing it to gradually separate from the wound bed. This is slower than surgical removal but less invasive. Autolytic debridement is the gentlest option: it relies on the body’s own immune cells and enzymes to dissolve dead tissue. Moisture-retentive dressings are applied to create a wet environment that softens the eschar over time. This approach is highly selective, meaning it targets only dead tissue and leaves healthy tissue intact, but it requires a functioning immune system to work.
When Eschar Is Left Alone
Not every eschar needs to be removed. In some cases, leaving it in place is the safer choice. Current wound care guidelines are clear on one scenario in particular: a dry, intact eschar on the heel that shows no signs of infection (no redness, swelling, or drainage) should not be softened or removed. This recommendation achieved strong consensus among wound care specialists, with 81% agreement at a major 2016 staging conference. The intact eschar acts as a natural biological covering, protecting the wound bed beneath it.
The same principle applies to patients with poor blood flow to their limbs. If an eschar is dry and stable but the patient has compromised circulation that cannot be restored, removing it could expose tissue that has no capacity to heal, creating a larger problem than the eschar itself. In these situations, the eschar is monitored closely and only debrided if signs of infection develop. For patients with multiple serious health conditions and limited mobility, a dry heel eschar may be left intact indefinitely as long as it remains stable.
Research on eschar preservation has also revealed a counterintuitive finding: in some wound types, keeping the eschar in place actually reduces inflammation and prevents excessive scarring. Studies show that preserved eschars dampen the inflammatory response in the wound, reducing immune cell activity and lowering levels of key inflammatory signals. Wounds with the eschar removed showed roughly twice the immune cell infiltration in the early days of healing and significantly more collagen buildup by day 21, which contributes to thicker, more contracted scars. This suggests the eschar can serve as a natural modulator of the healing process, not just a passive barrier.