Merck Manual

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Pressure Sores

(Bedsores; Decubitus Ulcers; Pressure Ulcers; Pressure Injuries)


Joshua S. Mervis

, MD, Tufts University School of Medicine;

Tania J. Phillips

, MD, Boston University School of Medicine

Reviewed/Revised Sep 2023
Topic Resources

Pressure sores are areas of skin damage resulting from a lack of blood flow due to prolonged pressure.

  • Pressure sores often result from pressure combined with pulling on the skin, friction, and moisture, particularly over bony areas.

  • The diagnosis is usually based on a physical examination.

  • Treatment includes cleansing, reducing pressure on the affected area, special dressings, and sometimes antibiotics and/or surgery.

  • With appropriate treatment, early-stage pressure sores often heal well.

  • Frequent repositioning and meticulous care of the skin are the best ways to prevent pressure sores.

Pressure sores occur where there is pressure on the skin from a bed, wheelchair, cast, splint, poorly fitting artificial (prosthetic) device, or other object. The most common places pressure sores occur are where bone is close to the skin, such as over the hip bones, tailbone, heels, ankles, and elbows, but they can occur anywhere.

Pressure sores lengthen the time spent in hospitals or nursing homes. They can be life threatening if they are untreated or if underlying health conditions prevent them from healing.

An estimated 2.5 million people in the United States develop pressure sores each year, resulting in a significant financial burden to people and the health care system. The number of affected people is on the rise, mainly because of the aging population.

Worldwide, pressure sores caused 24,400 deaths in 2019.

Common Sites for Pressure Sores

Common Sites for Pressure Sores

Risk Factors

Risk factors for pressure sores include the following:

Pressure sores occur most frequently in older adults because their skin may be thinner and may heal more slowly. The sores often develop in people after they have been hospitalized for a different medical problem that limits their ability to move or shift around.

Inadequate nutrition Undernutrition Undernutrition is a deficiency of calories or of one or more essential nutrients. Undernutrition may develop because people cannot obtain or prepare food, have a disorder that makes eating or... read more Undernutrition increases the risk of developing pressure sores and slows the healing process of sores that do develop. Undernourished people may not have enough body fat to cushion the tissue. Also, the skin heals poorly if people are undernourished, particularly if they are deficient in protein, vitamin C, or zinc.

Spotlight on Aging: Pressure Sores

Aging itself does not cause pressure sores. But it causes changes in tissues that make pressure sores more likely to develop. As people age, the outer layers of the skin thin. Many older adults have less fat and muscle, which help absorb pressure. The number of blood vessels decreases, and blood vessels rupture more easily. All wounds, including pressure sores, heal more slowly.

Certain risk factors make pressure sores more likely to develop in older adults:

Did You Know...

  • Inadequate nutrition increases the chances of developing pressure sores and slows the healing of sores that do develop.

Causes of Pressure Sores

Causes that contribute to the development of pressure sores include

  • Pressure

  • Traction

  • Friction

  • Moisture


Pressure on skin, especially when over or between bony areas, reduces or cuts off blood flow to the skin. Pressure can be caused by a bed, wheelchair, cast, splint, poorly fitting artificial (prosthetic) device, or other object. If blood flow is cut off for more than a few hours, the skin dies, beginning with its outer layer (epidermis). The dead skin breaks down and an open sore (ulcer) develops.

Most people do not develop pressure sores because they constantly shift position without thinking, even when they are asleep. However, some people cannot move normally and are therefore at greater risk of developing pressure sores. They include people who are paralyzed, comatose, very weak, sedated, or restrained. People who are paralyzed or comatose are at particular risk because they also may be unable to move or feel pain (pain normally motivates people to move or to ask to be moved).


Traction is a sideways pulling force on the skin. It also reduces blood flow to the skin.

Traction occurs when, for example, people are placed on an incline (such as when they are made to sit up on an inclined bed) and their skin becomes stretched. Muscles and tissues under the top layer of skin are drawn down by gravity, but the top layers of skin remain in contact with the outer surface (such as bed linens). When the skin is stretched, the effect is much like pressure.


Friction is the skin rubbing against clothing or bedding. It can lead to or worsen pressure sores. Repeated friction may wear away the top layers of skin. Such skin friction may occur, for example, if people are pulled repeatedly across a bed.


Symptoms of Pressure Sores

For most people, pressure sores cause some pain and itching. However, in people whose senses are dulled, even severe sores may be painless.

Pressure sores are categorized into four stages (1 to 4) according to the severity of soft-tissue damage. Pressure sores do not always progress from mild to severe stages. Sometimes the first noticeable sign is a stage 3 or 4 sore.

Stage 1: On light skin, the skin is red or pink. On dark skin, there may be no changes in skin color.

The skin may also be warmer, cooler, firmer, softer, or more tender than nearby skin that is not injured by pressure. At this stage, an actual ulcer is not yet present (the skin is not broken).

Stage 2: The pressure sore is shallow with a pink to red base. Some skin may be lost, and blisters may develop. Deeper tissues beneath the sore cannot be seen.

Stage 3: The skin over the sore is worn away. The sore sometimes goes down to the layer of fat, but deeper structures beneath the sore, such as muscles and bones, cannot be seen.

Stage 4: The skin is worn away all the way through, making the deep structures beneath the sore, such as muscles, tendons, and bones, visible.

Examples of Pressure Sore Stages 1–4

Unstageable: Sometimes doctors cannot determine what stage a pressure sore is. For example, pressure sores that are covered with debris or a thick, crusty surface (eschar) cannot be staged unless the debris or eschar is removed.

Deep-tissue pressure injury: These injuries are purple- to maroon-colored areas of broken or unbroken skin or blood-filled blisters that are caused by damage to the underlying soft tissues. The area may feel firmer, mushier, warmer, or cooler than surrounding tissue.

Medical device–related pressure injury: These injuries result from the use of devices designed and applied for treatment purposes. Long-term use of medical devices, especially if they are poorly placed or ill-fitting, can cause injury to skin or mucous membranes (the moist surfaces or inner linings of some parts of the body).

For example, masks or tubing used for people who need oxygen can cause pressure sores on the bridge of the nose, the ears, the back of the head, or wherever the mask or tubing applies pressure. Poorly fitting dentures or an improperly secured endotracheal tube can cause pressure sores inside the mouth. Injuries typically conform to the pattern or shape of the device.

Doctors are usually able to determine a stage for medical device–related pressure injuries to the skin but not to the mucous membranes.

Complications of Pressure Sores

Bacterial infection is the most common complication of pressure sores. If pressure sores become infected, they may have an unpleasant odor. Pus may be visible in or around the sore. The area around the sore may become red or feel warm, and pain may worsen if the infection spreads to the surrounding skin and tissues beneath the skin. Some people may have a fever. Infection delays healing of shallow sores and can be life threatening in deeper sores.

Infection in pressure sores that do not heal may cause cellulitis Cellulitis Cellulitis is a spreading bacterial infection of the skin and the tissues immediately beneath the skin. This infection is most often caused by streptococci or staphylococci. Redness, pain, and... read more Cellulitis and sinus tracts to form. Cellulitis is a spreading bacterial infection of the skin and the tissues immediately beneath the skin. Sinus tracts are passages that connect the infected area of the skin surface or the sore to other structures, such as those deep in the body. For example, a sinus tract from a pressure sore near the pelvis can connect to the bowel (this abnormal connection is called a fistula). Infection can even penetrate the bone (osteomyelitis Osteomyelitis Osteomyelitis is a bone infection usually caused by bacteria, mycobacteria, or fungi. Bacteria, mycobacteria, or fungi can infect bones by spreading through the bloodstream or, more often, by... read more ) or a joint (infectious arthritis Infectious Arthritis Infectious arthritis is infection in the fluid and tissues of a joint usually caused by bacteria but occasionally by viruses or fungi. Bacteria, viruses, or fungi may spread through the bloodstream... read more ), or it can rapidly spread to destroy muscle and other deep tissues (necrotizing fasciitis Necrotizing Skin Infections Necrotizing skin infections, including necrotizing cellulitis and necrotizing fasciitis, are severe forms of cellulitis. These infections cause infected skin and tissues to die (necrosis). The... read more Necrotizing Skin Infections ).

Diagnosis of Pressure Sores

  • A doctor's evaluation

  • Staging of the sore

  • Assessment of nutrition status

  • Sometimes blood tests and magnetic resonance imaging

Doctors can usually diagnose pressure sores by doing a physical examination and noting the appearance and location of the sores.

Because the depth and severity of pressure sores are difficult to determine, doctors or specially trained health care professionals stage and photograph pressure sores to monitor how they progress or heal. Doctors use specific criteria to determine how a pressure sore is healing.

Doctors also assess people for their nutrition status by examining them and asking about their food intake and weight changes.

People with pressure sores, especially those with stage 3 or 4 sores, sometimes have blood tests. Sometimes a blood sample is cultured to see whether infection has spread to the bloodstream.

When pressure sores do not heal, doctors often suspect a complication such as an infection. If osteomyelitis is suspected, doctors do blood tests and often the imaging test magnetic resonance imaging Magnetic Resonance Imaging (MRI) Magnetic resonance imaging (MRI) is a type of medical imaging that uses a strong magnetic field and very high frequency radio waves to produce highly detailed images. During an MRI, a computer... read more Magnetic Resonance Imaging (MRI) (MRI). To confirm osteomyelitis, doctors may need to take a small sample (biopsy) of bone to see if bacteria grow from it (culture).

Treatment of Pressure Sores

  • Pressure relief

  • Wound cleaning and dressing

  • Pain management

  • Infection control

  • Good nutrition

  • Sometimes surgery

Treating a pressure sore is much more difficult than preventing one.

The main goals of treatment are to relieve pressure on the sores, clean and dress the wounds appropriately, control infection, and provide adequate nutrition. Sometimes surgery is needed to close large wounds.

Pressure relief

To relieve pressure on the skin, people require careful positioning, protective devices, and support surfaces. In the earliest stage, pressure sores usually heal by themselves once pressure is removed.

Frequent repositioning (and selection of the proper position) is the main way to relieve pressure. People confined to bed should be turned a minimum of every 1 to 2 hours and should be placed at an angle to the mattress when on their side to avoid direct pressure on the hips. Elevation of the head of the bed should be minimal to avoid the effects of traction. When people are being repositioned, to avoid unnecessary friction, lifting devices or bed linen should be used instead of dragging people. Doctors may instruct caregivers to follow a written schedule to direct and document repositioning. People who are placed in a chair should be repositioned every hour and encouraged to change position on their own if they can every 15 minutes. Otherwise, caregivers should help people change positions.

Protective padding such as pillows, foam wedges, and heel protectors can be placed between and/or under the knees, ankles, and heels when people are lying on their back or on their side. Bony areas such as heels and elbows can be protected with soft materials such as foam wedges and heel protectors. Soft seat cushions are given to people who are able to sit in a chair.

Support surfaces, such as foam and other types of mattresses, that are placed under people confined to bed can be changed to reduce pressure. They are used in hospitals, nursing homes, and sometimes in private homes. Support surfaces are classified based on whether they require electricity to operate. Static surfaces do not require electricity, whereas dynamic surfaces do.

Static surfaces include air, foam, gel, and water overlays and mattresses. Egg-crate mattresses are not helpful for relieving pressure. In general, static surfaces increase the area over which weight is distributed, thus decreasing pressure and traction. Static surfaces have traditionally been used to prevent pressure sores or to treat stage 1 pressure sores.

Dynamic surfaces include alternating-air mattresses, low-air-loss mattresses, and air-fluidized mattresses. Alternating-air mattresses have air cells that are alternately inflated and deflated by a pump, which shifts supportive pressure from site to site. Low-air-loss mattresses are giant air-permeable pillows that are continuously inflated with air. The air flow has a drying effect on tissues. Air-fluidized mattresses circulate air. They reduce moisture and provide cooling. Dynamic surfaces are used if a pressure ulcer does not heal when a static surface is used.

Wound cleaning and dressing

To heal, pressure sores need to be cleaned, dead skin needs to be removed (a process called debridement), and dressings need to be applied.

The wound is cleaned when the dressing is changed. Health care professionals often flood (irrigate) the wound, particularly its deep crevices, with saline to help loosen and clean away hidden debris.

A doctor may need to remove dead tissue with a scalpel, a chemical solution, a whirlpool bath (hydrotherapy), a special dressing, or biosurgery (using medical maggots to remove dead tissue). Removal of dead tissue is usually painless, because pain is not felt in dead tissue. Some pain may be felt because healthy tissue is nearby.

Dressings Dressings Topical medications are medications applied directly to the skin. They are a mainstay of treating skin disorders. Systemic medications are taken by mouth or given by injection and are distributed... read more are used to protect the wound and promote healing. They are used for some stage 1 pressure sores and for all other pressure sores. When the skin is broken, a doctor or nurse considers the location and condition of the pressure sore when recommending a dressing. The amount of drainage oozing from the sores helps determine which type of dressing is best.

  • Transparent (clear) films or hydrogels help protect stage 1 pressure sores or shallow pressure sores that have minimal drainage or dry crust (eschar) and allow them to heal more quickly. Transparent films and hydrogels are changed every 3 to 7 days.

  • Hydrocolloid (oxygen-retaining and moisture-retaining) patches protect pressure sores and provide a healthy environment for sores with light drainage. These patches can be left in place for up to 1 week depending on the amount of drainage.

  • Alginates (made from seaweed), which come as pads, ropes, ribbons, and hydrofiber dressings, are used for pressure sores with a lot of drainage and to control bleeding after surgical debridement. Alginates can be used for up to 7 days but must be changed earlier if they become saturated with fluid.

  • Foam dressings can be used in sores that drain various amounts of fluid. Foam dressings must be changed every 3 to 4 days. Waterproof versions protect the pressure sores from perspiration, urine, and feces.

Pain management

Infection control

Superficial infections can sometimes be treated with antibiotics that are applied directly to the skin. Doctors also give antibiotics taken by mouth or given by vein if people have infection that has spread, for example, to deeper tissue, the skin beyond the sore, the bone, or the bloodstream.



Deep or large pressure sores are difficult to treat. Sometimes they need to be closed with skin grafts and flaps with skin and sometimes muscle. In these procedures, healthy, thicker tissue with a good blood supply is surgically repositioned to cover the damaged area.

Skin grafts are useful for large, shallow pressure sores. Flaps with skin and muscle are used to close pressure sores over large bony areas (usually the base of the spine, hips, and the upper end of the thighbones).

Surgery improves quality of life for some people. However, it is not always successful, especially for frail older adults who are undernourished and have other disorders.

Prognosis for Pressure Sores

The prognosis for early-stage pressure sores is excellent if people have received timely, appropriate treatment, but healing typically requires weeks. After 6 months of treatment, more than 70% of stage 2 pressure sores, 50% of stage 3 pressure sores, and 30% of stage 4 pressure sores resolve.

Pressure sores often develop in people who are receiving inadequate care, have disorders that impair wound healing (such as diabetes or undernutrition), or both. Without continual meticulous care of the sores and treatment of other disorders and complications, long-term prognosis is poor, even if pressure sores have healed.

Prevention of Pressure Sores

  • Frequent repositioning

  • Meticulous hygiene and care of skin

  • Maintaining movement

Prevention is the best strategy for dealing with pressure sores. In most cases, pressure sores can be prevented by meticulous attention from all caregivers, including nurses, nurses’ aides, and family members.

Frequent repositioning is the best way to avoid pressure sores. People who cannot move themselves should be repositioned frequently. For example, people who are confined to bed should be repositioned at least every 1 to 2 hours. People who are placed in a chair should be repositioned every hour. If they are capable, they should be encouraged to change position on their own every 15 minutes.

Every day, caregivers should closely inspect the skin to look for early signs of redness or discoloration. Any sign of redness or discoloration at pressure areas is a signal that the person needs to be repositioned and kept from lying or sitting on the discolored area until it returns to normal.

Did You Know...

  • Repositioning people who cannot move themselves (every hour for those in a chair and every 1 to 2 hours for those in a bed) can help prevent pressure sores.

Skin care is vital to preventing pressure sores. The skin must be kept clean and dry because moisture increases the risk of developing pressure sores. Dry skin is less likely to stick to fabrics and cause friction or traction. After cleaning, the skin should be dried by gentle patting (avoiding rubbing the skin). The use of thick creams that act as a barrier to protect the underlying skin from moisture may help prevent sores. For people confined to bed, sheets and clothing should be changed frequently to make sure they are clean and dry. Cornstarch may allow microorganisms to grow and should not be used, but plain talc can be used in areas subject to friction.

Bony areas (such as heels and elbows) can be protected with soft materials, such as foam wedges and heel protectors. Protective padding, pillows, or sheepskin can be used to separate body surfaces. Special beds, mattresses, and seat cushions can reduce pressure and offer extra relief to people who use a wheelchair or are confined to bed. A doctor or nurse can recommend the most appropriate mattress surface or seat cushion. It is important to remember that these devices do not eliminate pressure completely and are not substitutes for frequent repositioning.

Movement is an important part of pressure sore prevention. People who have difficulty moving or who are immobilized are at risk of developing pressure sores, so activity should be encouraged. Medications that induce sleep (sedatives Misuse of Antianxiety Medications and Sedatives Antianxiety and sedative medications are prescription drugs used to relieve anxiety and/or help with sleep, but their use can result in dependency and a substance use disorder. Using prescription... read more ) should be reduced or avoided because people who are sleepy are less likely to change position.

Drugs Mentioned In This Article

Generic Name Select Brand Names
7T Gummy ES, Acephen, Aceta, Actamin, Adult Pain Relief, Anacin Aspirin Free, Aphen, Apra, Children's Acetaminophen, Children's Pain & Fever , Children's Pain Relief, Comtrex Sore Throat Relief, ED-APAP, ElixSure Fever/Pain, Feverall, Genapap, Genebs, Goody's Back & Body Pain, Infantaire, Infants' Acetaminophen, LIQUID PAIN RELIEF, Little Fevers, Little Remedies Infant Fever + Pain Reliever, Mapap, Mapap Arthritis Pain, Mapap Infants, Mapap Junior, M-PAP, Nortemp, Ofirmev, Pain & Fever , Pain and Fever , PAIN RELIEF , PAIN RELIEF Extra Strength, Panadol, PediaCare Children's Fever Reducer/Pain Reliever, PediaCare Children's Smooth Metls Fever Reducer/Pain Reliever, PediaCare Infant's Fever Reducer/Pain Reliever, Pediaphen, PHARBETOL, Plus PHARMA, Q-Pap, Q-Pap Extra Strength, Silapap, Triaminic Fever Reducer and Pain Reliever, Triaminic Infant Fever Reducer and Pain Reliever, Tylenol, Tylenol 8 Hour, Tylenol 8 Hour Arthritis Pain, Tylenol 8 Hour Muscle Aches & Pain, Tylenol Arthritis Pain, Tylenol Children's, Tylenol Children's Pain+Fever, Tylenol CrushableTablet, Tylenol Extra Strength, Tylenol Infants', Tylenol Infants Pain + Fever, Tylenol Junior Strength, Tylenol Pain + Fever, Tylenol Regular Strength, Tylenol Sore Throat, XS No Aspirin, XS Pain Reliever
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