Pressure sores are areas of damaged skin and tissue caused by sustained pressure that cuts off blood flow, typically over bony parts of the body like the tailbone, heels, and hips. They affect roughly 2.5 million people per year in the United States alone, and about 60,000 of those cases are fatal. You may also hear them called bedsores, pressure ulcers, or pressure injuries, which is the term medical professionals now prefer since the damage can occur even before the skin visibly breaks open.
How Pressure Sores Form
Your body’s smallest blood vessels, called capillaries, deliver oxygen and nutrients to every layer of tissue. When an area of skin is compressed between a bone and a hard surface (a mattress, a wheelchair seat, even a shoe), those capillaries get squeezed shut. Normal capillary pressure ranges from about 12 to 32 mm Hg, and anything exceeding that range starves the tissue of oxygen. If that compression isn’t relieved, a pressure sore can begin forming in as little as three to four hours.
Muscle tissue is actually more vulnerable to this oxygen loss than skin. That means damage sometimes starts deep, beneath layers of intact-looking skin, and works its way outward. Once blood flow is cut off long enough, the affected tissue triggers an inflammatory response: fluid builds up, cells begin dying, and even restoring blood flow can cause further injury to already weakened tissue. This is why pressure sores can seem to appear suddenly or worsen quickly once they become visible on the surface.
Where They Develop
Pressure sores form wherever bone sits close to the skin with little fat or muscle padding in between. For someone lying in bed, the most common sites are the tailbone (sacrum), the back of the heels, the shoulder blades, and the back of the head. For someone sitting in a wheelchair, the greatest risk is on the sitting bones (ischial tuberosities) and the tailbone. Elbows, ankles, and the outer edges of the hips are also vulnerable depending on positioning. Essentially, any spot where you can feel bone just beneath the skin is a potential pressure point.
Stages of Severity
Pressure sores are classified in stages that reflect how deep the damage goes:
- Stage 1: The skin is intact but shows a persistent red or discolored area that doesn’t fade when you press on it. On darker skin tones, this may appear purple or ashen rather than red. The area may feel warmer, firmer, or more painful than surrounding skin.
- Stage 2: The outer layer of skin has broken open or worn away, creating a shallow wound that looks like a blister or a raw, pinkish crater.
- Stage 3: The damage extends through the full thickness of the skin into the fat layer beneath, forming a deeper crater. Bone, tendon, and muscle are not yet exposed.
- Stage 4: The wound reaches bone, muscle, or tendon. These injuries carry the highest risk of life-threatening infection and often require surgical intervention.
Some pressure injuries can’t be staged at all because the wound bed is covered in dead tissue that obscures how deep the damage goes. These are classified as “unstageable” until the dead tissue is removed.
Who Is Most at Risk
Anyone who stays in one position for extended periods is at risk, but several factors make pressure sores far more likely. Clinicians assess risk using six key dimensions: the ability to feel discomfort from pressure (sensory perception), skin moisture, physical activity level, the ability to change position independently, nutritional status, and exposure to friction or shearing forces. A person who scores poorly in multiple categories faces significantly elevated risk.
In practical terms, the highest-risk groups include people with spinal cord injuries who can’t feel or respond to pressure, older adults with limited mobility, patients recovering from surgery or in intensive care, and anyone with conditions that reduce blood flow, such as diabetes or peripheral vascular disease. Poor nutrition compounds the problem: when your body lacks the raw materials to maintain and repair tissue, even moderate pressure can cause damage faster. People who are incontinent face extra risk because persistent moisture softens and weakens skin, making it more susceptible to breakdown.
Serious Complications
Left untreated, pressure sores can become gateways for dangerous infections. Bacteria from an open wound can spread into the surrounding skin (cellulitis) or enter the bloodstream, a condition called septicemia that can be life-threatening. Deep pressure sores sometimes develop sinus tracts, which are tunnel-like passages that connect the wound to structures deeper in the body. These tracts can lead to bone infections (osteomyelitis), joint infections, bacterial meningitis, or heart valve infections. In severe cases, a type of rapidly spreading tissue destruction known as necrotizing fasciitis can develop. Pressure sores cost the U.S. healthcare system between $9.1 and $11.6 billion per year, with the cost of treating a single pressure sore ranging from roughly $20,900 to over $150,000.
Treatment Approaches
Treating a pressure sore depends entirely on its stage. Stage 1 injuries often resolve with pressure relief alone: removing the source of compression, repositioning, and protecting the area. Once the skin has broken, wound care becomes essential. The goal is to keep the wound moist (which promotes healing), remove dead tissue, and prevent infection.
Dead tissue removal, called debridement, can happen several ways. A clinician may physically cut away the damaged tissue, use high-pressure irrigation to flush it out, or apply topical agents that chemically break down necrotic material. Dressings are chosen to maintain a moist wound environment without sticking to the healing tissue underneath. A nonstick, porous layer goes directly on the wound, often followed by an absorbent layer and a protective outer covering. Getting this right matters: if a dressing dries out and bonds to the wound, removing it tears away the fragile new tissue trying to form.
Stage 3 and 4 wounds may require surgical repair, including skin grafts or tissue flaps, and recovery can take weeks to months. Throughout treatment, the underlying cause of pressure must also be addressed, or the wound will simply return.
The Role of Nutrition in Healing
Healing a pressure sore places significant demands on the body, and nutrition is a critical factor that’s often overlooked. Adults with existing pressure injuries or at high risk of developing them need substantially more protein than usual. Guidelines recommend 1.25 to 1.5 grams of protein per kilogram of body weight daily. For a 150-pound person, that works out to roughly 85 to 100 grams of protein per day, well above the typical recommended intake. People with severe wounds may need even more, up to 2.0 grams per kilogram daily.
Vitamins and minerals also play a role. Vitamin C, zinc, and copper are all involved in tissue repair. Zinc supplementation can help when a deficiency is present, but doses above 40 mg per day can actually cause harm by interfering with copper absorption and potentially leading to anemia. The overall message is straightforward: calories and protein fuel wound healing, and deficiencies in either will slow recovery or stall it entirely. If someone with a pressure sore is eating poorly or losing weight, addressing nutrition is just as important as wound care itself.
Prevention Strategies
Repositioning is the cornerstone of prevention. For people who cannot move independently, current guidelines suggest changing position every two to three hours when in bed, provided they’re also on an appropriate pressure-redistributing mattress. Simply shifting position in a chair should happen even more frequently, roughly every 15 to 30 minutes. These intervals aren’t one-size-fits-all. Someone who is critically ill or has poor circulation may need to be repositioned more often, while someone whose risk is decreasing and who can shift their own weight may gradually extend the interval.
Specialty mattresses and cushions designed to distribute weight more evenly across the body make a real difference. These range from basic foam overlays to sophisticated alternating-pressure air mattresses that continuously shift the areas bearing weight. Keeping skin clean and dry, especially for people dealing with incontinence, reduces the moisture-related weakening that makes skin vulnerable. Barrier creams can help protect intact skin in high-risk areas.
Daily skin checks are essential for anyone at risk. This means visually inspecting all bony prominences, paying close attention to the tailbone, heels, and hips. Catching a stage 1 pressure injury, a persistent red patch that doesn’t blanch, gives you the chance to intervene before the skin breaks down further. Adequate nutrition, keeping the body well-supplied with protein and micronutrients, supports the skin’s ability to withstand and recover from pressure.