Pressure Ulcer Stages Explained: From Stage 1 to Stage 4

Written by Jennifer Chen Wound Care Specialist, CWCN Jan 23, 2026

Understanding How Pressure Ulcers Are Classified

Pressure ulcers, also called bedsores or pressure injuries, are classified into stages based on the depth and severity of tissue damage. Understanding these stages helps patients, families, and caregivers recognize the seriousness of wounds, communicate effectively with healthcare providers, and appreciate the importance of both prevention and early treatment.

The staging system provides a common language for describing pressure ulcers and guides treatment decisions. Each stage represents progressively deeper tissue damage, with earlier stages being more treatable and later stages requiring intensive intervention.

This guide explains each pressure ulcer stage, what it looks like, and what it means for treatment and healing.

How Pressure Ulcers Develop

Before examining the stages, understanding how pressure ulcers form helps explain why they progress through increasingly serious phases.

The Role of Pressure

Pressure ulcers develop when sustained pressure compresses tissue between a bony prominence and an external surface like a mattress or chair. This compression restricts blood flow, depriving tissue of oxygen and nutrients.

Without adequate blood supply, tissue begins to die. The longer pressure continues, the deeper damage extends. What begins as surface damage can progress to involve deeper tissue layers including fat, muscle, and even bone.

Contributing Factors

Several factors increase vulnerability to pressure damage including immobility that prevents natural position shifting, reduced sensation that eliminates warning pain, moisture from incontinence or perspiration, poor nutrition that weakens tissue, friction and shear forces, and conditions affecting circulation.

Common Locations

Pressure ulcers most commonly develop over bony prominences where pressure concentrates. Frequent sites include the sacrum and tailbone, hips, heels, shoulder blades, back of the head, and elbows.

Stage 1 Pressure Ulcers

Stage 1 represents the earliest identifiable pressure damage, involving only the outermost skin layer.

Appearance

Stage 1 pressure ulcers appear as areas of non-blanchable redness on intact skin. When you press on normal skin, it briefly turns white (blanches) then returns to normal color. In Stage 1 pressure ulcers, the redness does not blanch when pressed.

In people with darker skin tones, Stage 1 may not appear as redness. Instead, the area may look purple, blue, or ashen compared to surrounding skin.

Other Signs

Beyond color changes, Stage 1 areas may feel different from surrounding skin. The area might be warmer or cooler than adjacent tissue, firmer or softer than normal, or painful or itchy.

Significance

Stage 1 pressure ulcers are a warning sign that tissue is being damaged. The skin is still intact, and damage is reversible if pressure is relieved promptly. However, Stage 1 indicates that without intervention, more serious damage will follow.

Treatment

Stage 1 treatment focuses on relieving pressure and protecting the area. Remove all pressure from the affected site. Increase repositioning frequency. Apply protective dressings if needed. Address contributing factors like moisture. Monitor closely for improvement or progression.

With prompt intervention, Stage 1 pressure ulcers typically resolve within a few days.

Stage 2 Pressure Ulcers

Stage 2 involves partial-thickness skin loss, meaning the damage extends through the outer skin layer into the underlying dermis.

Appearance

Stage 2 pressure ulcers present as shallow open wounds with a red or pink wound bed. They may also appear as intact or ruptured fluid-filled blisters.

The wound bed is moist and may be painful. There is no slough (yellow dead tissue) or eschar (black dead tissue) visible in Stage 2 wounds.

What Stage 2 Is Not

Not all skin damage is a pressure ulcer. Stage 2 should not be used to describe skin tears, tape burns, incontinence-associated dermatitis, maceration, or excoriation. These conditions may look similar but have different causes and treatments.

Significance

Stage 2 indicates more significant damage than Stage 1. The protective skin barrier has been broken, creating infection risk. However, Stage 2 wounds still have good healing potential with appropriate care.

Treatment

Stage 2 wounds require proper wound care in addition to pressure relief. Keep the wound clean and protected. Apply appropriate dressings to maintain moisture balance. Continue aggressive pressure relief. Monitor for signs of infection. Consider professional wound care evaluation.

Stage 2 pressure ulcers typically heal within several weeks with proper care.

Stage 3 Pressure Ulcers

Stage 3 represents full-thickness skin loss, with damage extending through the entire skin into the subcutaneous fat layer.

Appearance

Stage 3 wounds present as deep craters. The subcutaneous fat may be visible in the wound bed, but bone, tendon, and muscle are not exposed.

Slough (yellow dead tissue) may be present but does not obscure the depth of tissue loss. Undermining and tunneling may occur, where the wound extends beneath the skin surface.

Depth Variation

Stage 3 depth varies by anatomical location. Areas with significant subcutaneous tissue, like the buttocks, can develop very deep Stage 3 wounds. Areas with minimal fat, like the nose or ear, may have relatively shallow Stage 3 wounds.

Significance

Stage 3 wounds are serious injuries requiring professional medical care. Healing takes months rather than weeks. Infection risk is substantial. Complications can be life-threatening.

Treatment

Stage 3 pressure ulcers require comprehensive professional wound care. Treatment involves thorough wound assessment and documentation, debridement to remove dead tissue, appropriate dressings for wound characteristics, aggressive pressure elimination, nutritional support, treatment of infection if present, and ongoing professional monitoring.

Skilled nursing through home health can provide professional Stage 3 wound care at home.

Stage 4 Pressure Ulcers

Stage 4 is the most severe classification, involving full-thickness tissue loss with exposed bone, tendon, or muscle.

Appearance

Stage 4 wounds are deep, often extending to bone. Bone, tendon, muscle, or cartilage may be directly visible or palpable in the wound bed.

Slough and eschar are often present. Undermining and tunneling frequently occur, sometimes extensively. The visible wound opening may not reflect the true extent of tissue destruction beneath the surface.

Significance

Stage 4 pressure ulcers are severe, potentially life-threatening wounds. They indicate extensive tissue destruction that developed over time. Healing requires months to years of intensive treatment, and some Stage 4 wounds never fully heal.

Complications of Stage 4 wounds include bone infection (osteomyelitis), sepsis, and death. These wounds demand aggressive professional intervention.

Treatment

Stage 4 treatment is complex and often requires multidisciplinary care. Components may include surgical debridement, treatment of bone infection, advanced wound therapies, specialized pressure-redistributing surfaces, nutritional optimization, and in some cases surgical reconstruction.

Many Stage 4 wounds require management in specialized wound care settings, though ongoing home health wound care plays a role in long-term management.

Unstageable Pressure Ulcers

Some pressure ulcers cannot be staged because the wound bed is obscured.

When Staging Is Not Possible

If slough or eschar covers the wound bed so completely that the depth cannot be determined, the wound is classified as unstageable. The true stage is unknown until the dead tissue is removed.

Significance

Unstageable wounds are by definition at least Stage 3, and many prove to be Stage 4 once debrided. They should be treated as serious wounds requiring professional care.

Exception

Stable eschar on heels serves a protective function and should not be removed. Dry, intact heel eschar without signs of infection can be left in place and monitored.

Deep Tissue Pressure Injury

This category describes a specific type of pressure damage.

Appearance

Deep tissue pressure injury appears as persistent deep red, maroon, or purple discoloration of intact skin, or as a blood-filled blister. The area may be preceded by tissue that is painful, firm, mushy, boggy, warmer, or cooler than adjacent tissue.

What It Means

Deep tissue injury indicates damage to underlying soft tissue from pressure or shear. The discoloration results from damaged blood vessels and tissue beneath the skin surface.

Evolution

Deep tissue injuries may evolve rapidly, with thin eschar developing over the area. The wound may resolve without tissue loss, or may progress to reveal the full extent of injury, which could be Stage 3 or Stage 4 depth.

Why Staging Matters

Understanding pressure ulcer stages serves several important purposes.

Communication

Staging provides a common language for describing wounds. When healthcare providers discuss a Stage 2 or Stage 4 wound, everyone understands the general severity.

Treatment Planning

Different stages require different treatment approaches. Stage 1 may need only pressure relief, while Stage 4 requires complex multidisciplinary care.

Prognosis

Staging helps set realistic expectations for healing time and outcomes. Early-stage wounds heal faster and more completely than advanced wounds.

Prevention Focus

Understanding how wounds progress through stages emphasizes the importance of prevention and early intervention. Stopping progression at Stage 1 or 2 avoids the serious complications of advanced wounds.

Reverse Staging Is Not Used

An important note about staging: pressure ulcers do not reverse through stages as they heal. A Stage 4 wound does not become Stage 3, then Stage 2, then Stage 1 as it heals.

Once staged, a wound retains that classification. Documentation describes a healing Stage 4 wound, not a wound that has become Stage 2. This reflects the reality that healed pressure ulcer tissue is scar tissue, not normal tissue, and remains vulnerable to future breakdown.

Getting Professional Help

Any pressure ulcer beyond Stage 1 deserves professional evaluation. Stage 3 and Stage 4 wounds absolutely require professional wound care.

Home health wound care services bring professional assessment and treatment to patients at home. Skilled nursing can evaluate wounds, provide appropriate treatment, monitor healing, and coordinate with physicians about wound management.

If you or a loved one has a pressure ulcer at any stage, consult healthcare providers about appropriate care. Early professional intervention produces better outcomes and prevents progression to more serious stages.