Bed sores start as patches of discolored skin that don’t fade when you press on them, and they can progress to open wounds deep enough to expose fat, muscle, or even bone. Their appearance changes dramatically depending on the stage, and catching them early makes a significant difference in healing. Knowing exactly what to look for at each phase helps you act before a minor skin change becomes a serious wound.
The Earliest Sign: Stage 1
A stage 1 bed sore is still a closed wound. The skin remains intact, but you’ll notice a localized patch of redness, usually directly over a bony area like the tailbone, heel, hip, or shoulder blade. The key feature is that this redness doesn’t fade when you press on it. With normal skin irritation, pressing a finger against the red spot turns it white (or “blanches”) for a moment before the color returns. A stage 1 bed sore stays red no matter how firmly you press.
The discoloration persists for more than 20 minutes after pressure is relieved from the area. Beyond the color change, the spot often feels different from the surrounding skin. It may be noticeably warmer or cooler to the touch, and the texture can feel either unusually firm or slightly spongy. Some people report tenderness or pain at the site before any visible change appears at all, making pain one of the very first warning signs.
What Stage 1 Looks Like on Dark Skin
On darker skin tones, a stage 1 bed sore won’t show up as the classic redness described in most guides. Instead, the area may appear purple, blue, or darker than the surrounding skin. Research from the University of Wisconsin School of Nursing found that these color differences are frequently mistaken for bruises, delaying treatment. Purple discoloration over a pressure point is a red flag worth investigating, not dismissing.
Because visual cues are less obvious on dark skin, touch becomes especially important. Feel for areas that are warmer or cooler than the tissue around them, and press gently to check for spots that feel boggy (soft and waterlogged underneath) or unusually firm. Localized pain is another reliable indicator regardless of skin tone.
Stage 2: Broken Skin and Blisters
At stage 2, the surface of the skin has broken. You’ll see a shallow, open wound with a pinkish-red bed, similar to a scrape or abrasion. Some stage 2 sores appear as intact or partially ruptured blisters filled with clear or slightly yellowish fluid. The wound is superficial at this point, meaning it involves only the top layers of skin, but it’s clearly more than just a color change. There’s no bruising, no dead tissue covering the wound, and no visible fat underneath. If you see any of those features, the sore is more advanced than stage 2.
Stage 3: A Deeper Crater
Stage 3 marks full-thickness skin loss. The wound now extends through all layers of skin and into the fat beneath. What you see is a noticeable crater. The yellowish fatty tissue at the base of the wound may be visible, but you should not be able to see bone, tendon, or muscle. The edges of the wound can start to roll inward, and the sore may have developed tunneling, where the damage extends sideways beneath the surrounding skin, making the wound larger below the surface than it appears at the opening.
At this stage, you might also notice drainage from the wound. The surrounding skin can look red, swollen, or feel warm, which are signs of possible infection that need prompt attention.
Stage 4: Exposed Bone, Muscle, or Tendon
Stage 4 is the most severe visible category. The wound has destroyed skin, fat, and deeper tissues. Bone, muscle, or tendon is directly visible or can be felt at the base of the wound. These sores are often large and deep, with significant undermining or tunneling beneath the skin. The risk of serious infection, including bone infection, is high. The wound bed may contain areas of dead tissue alongside exposed structures.
Wounds That Can’t Be Staged
Sometimes a bed sore is clearly deep, but you can’t tell exactly how deep because the wound bed is covered by dead tissue. This is called an unstageable pressure injury, and it comes in two forms depending on what’s covering the wound.
Slough is soft, moist dead tissue that can appear yellow, tan, grey, green, or brown. It sits on the wound surface like a film or clumps of debris. Eschar is drier and tougher, forming a leathery covering that ranges from tan to brown to black. It can look like a thick scab. Until enough of this dead tissue is removed to reveal the wound base underneath, the true depth of the sore remains unknown. A wound covered in thick black eschar could be stage 3 or stage 4, but there’s no way to tell without clearing the surface.
Deep Tissue Injury: Damage From the Inside Out
Not all bed sores develop from the surface down. A deep tissue injury starts in the muscle and soft tissue beneath the skin, caused by intense or prolonged pressure, and works its way outward. On the surface, it appears as a purple or maroon patch of intact skin, or as a blood-filled blister. The color is distinctly different from a stage 1 sore, which looks red on lighter skin. Deep tissue injuries look more like a deep bruise.
These injuries can evolve rapidly. Within days, the area may develop a thin blister over a dark wound bed, then deteriorate quickly into a full-thickness wound. The deceptive part is that the surface appearance dramatically underestimates the damage happening underneath. What looks like a dark bruise on Monday can become a stage 3 or 4 wound by the end of the week.
Where Bed Sores Typically Appear
Bed sores form wherever bone presses skin against a surface for extended periods. The location depends on the person’s usual position. For someone lying on their back, the most common sites are the tailbone (sacrum), heels, shoulder blades, and the back of the head. For someone lying on their side, the hips, ankles, and ears are vulnerable. People who use wheelchairs tend to develop sores on the tailbone and the bony parts of the buttocks (ischial tuberosities), as well as the shoulder blades and backs of the arms or legs that rest against the chair.
Checking these specific areas regularly is the most practical way to catch a sore early. Run your fingers over bony prominences to feel for temperature changes, texture differences, or tenderness, then look for discoloration. On lighter skin, you’re looking for redness that doesn’t blanch. On darker skin, look for purple, blue, or any color that differs from the surrounding area.
How Quickly They Progress
A stage 1 sore can develop in as little as a few hours of unrelieved pressure, particularly in people with limited mobility, poor circulation, or thin skin. Progression from stage 1 to a more serious wound can happen within days if pressure isn’t relieved. Deep tissue injuries are especially unpredictable, sometimes deteriorating from intact skin to an open wound in 48 to 72 hours.
The good news is that stage 1 sores are fully reversible. Once pressure is removed, the discoloration should begin to fade. If a red or purple patch doesn’t start improving within a few hours of repositioning, it’s likely a true pressure injury rather than temporary irritation. Stage 2 sores can heal within weeks with proper care, while stage 3 and 4 wounds often take months and may require surgical intervention.