4 Stages of Pressure Ulcers

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If a loved one has been severely injured or is extremely ill, they may need to spend a significant amount of time in bed. Prolonged immobility, while beneficial to recovery, can become problematic if it places persistent pressure on vulnerable skin. Unless preventive steps are taken, pressure ulcers, also known as decubitus ulcers or bedsores, can develop.

Elderly woman in a hospital bed.
David Sacks / Getty Images


Pressure ulcers most often develop on skin that covers bony parts of the body, such as the ankles, heels, hip, and tailbone. Signs of a developing pressure ulcer include:

  • Unusual changes in skin color or texture
  • Swelling of the skin around bony parts of the body
  • Areas of extreme tenderness
  • Areas of skin that are cooler or warmer to the touch

Pressure ulcers fall into one of four stages based on their depth, severity, and physical characteristics. Early-stage ulcers may only cause red, unbroken skin; advanced ulcers can manifest with deep tissue injury involving exposed muscle and bone.


Pressure ulcers are caused by pressure placed against the skin for a long period of time. The pressure reduces the blood circulation to areas of skin, causing cell death (atrophy) and the breakdown of tissue.

The people most affected are those whose medical condition limits their ability to change position. This includes the elderly, people who have had a stroke, people with a spinal cord injury, or those with paralysis or a physical disability. For these and others, pressure ulcers can develop just as easily in a wheelchair as it can in bed.

For those confined to bed, common sites for pressure ulcers include:

  • The back or side of the head
  • Shoulder blades
  • Lower back, buttocks, hip, or tailbone
  • Heels, ankles, or behind the knees

For people confined to a wheelchair, common sites include:

  • Spine
  • Shoulder blades
  • Tailbone or buttocks
  • Part of the arms and legs that rest against the chair

Once a pressure ulcer forms, it can be difficult to treat. Understanding the different stages can help determine the best course of action.


Pressure ulcers are categorized by the National Pressure Ulcer Advisory Panel into four stages based on the degree of tissue involvement or the depth of the sore. The tissue layers can be broken down as:

  • Epidermis (the outermost layer of skin)
  • Dermis (the second layer of skin)
  • Hypodermis (the lower layer of skin made up of fat and connective tissues)
  • Fascia (the layer of soft connective tissue below the skin that encloses muscles, nerves, blood vessels, and internal organs)

Stage One

Stage one ulcers are characterized by the superficial reddening of intact skin that does not blanch when pressed. The skin may be warm to the touch and either feel firmer or softer than the surrounding skin. People with darker skin may experience visible discoloration.

Edema (tissue swelling) and induration (the hardening of tissues) may be indications of a stage one pressure ulcer. If the pressure is not removed, a stage one pressure ulcer can progress to stage two.

If diagnosed and treated immediately, a stage one pressure ulcer can usually resolve within three to four days.

Stage Two

Stage two ulcers are diagnosed when intact skin suddenly breaks open, exposing the epidermis and sometimes the dermis. The lesion will be superficial and often resemble an abrasion, popped blister, or shallow crater of skin. Stage two pressure ulcers will usually be red and warm to the touch. There may also be clear fluid in the broken skin.

To prevent progression to stage three, every effort must be made to pad the sore and alter the body's position frequently.

If treated properly, a stage two pressure ulcer can take anywhere from four days to three weeks to resolve.

Stage Three

Stage three ulcers are characterized by a lesion that extends well into the dermis and begins to involve the hypodermis (also known as the subcutaneous layer). By this stage, the lesion will form a small crater. Fat may begin to show in the open sore but not muscle, tendon, or bone. In some cases, there may be visible pus and a foul smell.

This type of ulcer opens the body to infection which can include signs of foul odor, pus, redness, and discolored drainage. It may lead to serious complications, including osteomyelitis (a bone infection) and sepsis (caused by an infection entering the bloodstream).

With aggressive and sustained treatment, a stage three pressure ulcer can resolve in one to four months depending on its size and depth.

Stage Four

Stage four pressure ulcers occur when the hypodermis and underlying fascia are breached, exposing muscle and bone. This is the most severe type of pressure ulcer and the most difficult to treat, with a high risk of infection. Damage to deeper tissues, tendons, nerves, and joints may occur, usually with copious amounts of pus and drainage.

Stage four pressure ulcers require aggressive treatment to avoid systemic infection and other potentially life-threatening complications. Mortality rates for elderly people with stage four pressure ulcers may be as high as 60% within one year, according to a 2014 study in Advances in Nursing.

Even with effective treatment in a care facility, a stage four pressure ulcer can take two to six months (or even longer) to heal.

Other Classifications

If a pressure ulcer is deep and mired in overlapping tissue, your healthcare provider may not be able to accurately stage it. This type of ulcer is considered unstageable and may require extensive debridement removal) of dead tissue before the stage can be determined.

Some pressure ulcers may appear on first glance to be stage one or stage two, but the underlying tissues may be more extensively damaged. In this case, the ulcer may be classified as stage one with a suspected deep tissue injury (SDTI). Upon further examination, an SDTI can sometimes turn out to be a stage three or four pressure ulcer.


If a loved one is hospitalized and unable to move, you need to be vigilant in recognizing—and ideally preventing—a pressure ulcer. A healthcare provider or physical therapist can work with you and the nursing team to ensure the following preventive measures:

  • Changing the body position every one to two hours
  • Using pressure-relieving pads over bony areas of skin, a special air or gel mattress, or a wheelchair cushion
  • Keeping the skin clean and dry
  • Avoiding scrubbing, strong soaps, and talcum powder
  • Taking care not to oversoak the skin
  • Using dry, soft, unwrinkled sheets and bedding
  • Using moisturizing cream and skin protectants every day
  • Avoiding dehydration
  • Regularly checking the fit of your wheelchair, especially if you gain or lose weight

Call your healthcare provider if you notice a sore, redness, warmth, or any other change in the skin that last for more than a few days. The earlier you treat a pressure ulcer, the better.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Laura Inverarity, DO
 Laura Inverarity, PT, DO, is a current board-certified anesthesiologist and former physical therapist.