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What is a Pressure Sore?

Last updated on 3rd May 2023

According to the BMJ, every year in the UK, more than 700,000 people are affected by pressure sores. Some 180,000 of these are new pressure sores. According to figures, pressure sores cost the NHS around £3.8 million every day. This equates to 4% of the total expenditure of the NHS.

Since the incidence and the co-occurring costs of these pressure ulcers are so high, it is important to understand the causes of pressure sores, how to treat them effectively and, more importantly, how to prevent their occurrence.

What is a pressure sore?

Pressure sores are often an avoidance and unwanted complication of care. They’re more common in people whose mobility is affected by a medical condition, disability, or age. They’re not only a problem in themselves but they can also lead to a reduced quality of life and increased mortality.

Pressure sores (also known as bedsores or pressure ulcers) are essentially injuries to a person’s skin and its underlying tissues caused by the skin being under pressure. Anyone can get a pressure sore but they’re more common in people who are confined to a bed or chair for a long period of time.

In medical terms, a pressure sore is described as localised, acute ischaemic damage to the tissue.

What causes a pressure sore?

Pressure sores are often located on areas of skin that cover bones. Examples of typical areas include the sacrum area, the hips, ankles and heels. These areas are the ones that are under more pressure and bear more weight when a person is confined to a chair or a bed for a long time.

The reason they happen is that the increased pressure on the skin’s surface reduces the skin’s blood flow. With reduced blood flow, the skin is more vulnerable to damage. This is because oxygen and nutrients can’t reach the tissues.

Loss of sensation is arguably the most common cause of pressure ulcers. When a patient can’t feel the pain or discomfort, they can’t react accordingly and move their body. This lack of sensation could be due to many different reasons, including congenital (e.g., spina bifida), traumatic (e.g., spinal injury), a disease (e.g., MS), or anaesthesia (e.g., pain relief like a spinal block).

When the skin is more fragile, it becomes more vulnerable to friction and can easily be damaged by rubbing on bed linen and clothes.

Another thing that can happen is a shear. This is when the surface of the skin and the surface below it move in opposite directions, thus creating a tear.

There are no set timescales after which these develop. They can come on in a matter of hours or days.

What is the first sign of a pressure sore?

There are a few signs to look out for when it comes to spotting pressure sores.

Here are some of the first signs:

  • Skin discolouration. With pale skin, you might see a red area, while with dark skin, you usually see blue or purple patches.
  • Discoloured patches of skin that don’t go pale when they’re pressed. Usually, when you press your skin, it briefly turns pale before going back to its original colour. When this doesn’t happen, it could be a sign of a pressure sore developing.
  • A patch of skin that feels hard, warm or spongy.
  • Itchy or painful skin.
  • Damage or blisters to the skin.

These first signs might be named a category 1 pressure sore.

Since pressure sores can come on in as little as two hours in some cases, it’s important to carry out regular checks for people who are more vulnerable. Identifying pressure sores at their first stages can save the patient from having a painful wound and can also save money and time for the NHS.

What are the signs and symptoms of a pressure sore?

The initial signs, as mentioned above, begin with discolouration of the skin. At this stage, the skin is intact but there might be blood-filled blisters present. In the early stages of a pressure sore, there might be pain but no tears or skin breaks. You might also notice swelling and warmth in the area compared to the surrounding skin.

As a pressure sore progresses to being partial thickness, common signs and symptoms include pain, the area being tender to the touch and ulcers developing.

When the pressure sore gets to full thickness, there will be pronounced ulcers in the skin (no muscle or bone will be visible). At this stage, patients might not feel any pain due to how much tissue is affected and destroyed.

If the pressure sore deteriorates even further, it will reach the muscle, tendon, joint and even bone. There will usually be pus that can be yellow, green, grey, brown or black.

Pressure Sore

Who is more at risk of getting a pressure sore?

There are several things that make a person more at risk of getting a pressure sore.

The most at risk are people who have mobility issues, whether temporarily or permanently. This is because they spend more time in bed or in a chair.

Here are some of the most important risk factors:


This is the biggest risk factor. Once a person is unable to move well, whether due to age, illness or disability, they are at a greater risk of developing pressure sores.

Sensory loss

When people lose sensation because of neurological diseases or spinal cord injury, there is an increased risk of them developing pressure sores. This is due to them being unable to feel any discomfort or pain. Without sensory loss, people normal shift position from time to time, but when sensory loss is present, this doesn’t feel necessary.

Mental status changes

If a person’s level of consciousness changes, they might not be awake enough to feel discomfort or they may be unable to reposition themselves if they do feel uncomfortable.


When a person suffers from incontinence, the risk of developing a pressure sore is greater. This is because moisture softens the skin and its connective tissues, which means shear and friction can be more damaging.

Faecal incontinence also comes with the added risk of bacteria in the stool which damages the skin further and opens people up to infection.

Poor nutrition

Being underweight means there is less padding on the bony areas of the body. This causes more pressure than if there were a layer of fat over the bony areas.

People who are obese are also at greater risk due to the added weight on their skin.


When a person gets older, not only does their mobility decrease but their skin is more fragile and thinner. This increases their risk of developing pressure sores.

Illnesses that affect blood flow

Illnesses like chronic heart disease and anaemia can also increase a person’s risk of pressure sores. With heart disease, the blood flow becomes sluggish, which affects the skin. With anaemia, the blood is not as effective at doing its job.

Chronic or acute susceptibility

As well as physical and mental risk factors, medical professionals also talk of chronic susceptibility and acute susceptibility.

Patients fall into one of these two groups. With acute susceptibility, the patient is at risk due to an operation or sudden trauma or illness. Their risk is usually for a short duration (typically two weeks at most) and as soon as the risk is removed, the patient isn’t susceptible anymore. An example of this might be in a patient who has been admitted to a high dependency ward for a short time after an operation. The patient might only be susceptible for a day or two until they are back on a normal ward without sedation and ventilation.

With chronic susceptibility, the risk period is either permanent or prolonged. This could be due to trauma or a degenerative disease. An example of this might be someone with a head injury or someone with a progressive neurological condition like Alzheimer’s disease or multiple sclerosis.

Dressing Pressure Sore

How to prevent a pressure sore?

Whenever anyone is deemed at risk of developing a pressure sore, there should be a risk assessment in place that dictates the practices to be undertaken to prevent them.

Some of the things that can be included in pressure sore prevention include:

  • Repositioning (advice to a patient and help with repositioning).
  • Checking skin a few times every day.
  • Changing any wet clothes or bedding straight away.
  • Changing position every two hours (if in a bed) or every hour (if in a wheelchair) – setting an alarm is helpful.
  • If repositioning a patient, the carer should lift and not slide them.
  • If the patient is in bed, their head should be as low down on the bed as possible to prevent sliding and friction.
  • Protect the skin on bony areas. This can be done with foam wedges and pillows, for example.
  • Keep skin clean and dry and moisturise the skin too. You shouldn’t use any products that contain alcohol and shouldn’t rub the skin with a towel – patting dry is advised.
  • The patient should be encouraged to have good nutrition and healthy foods. Hydration is important too.

When to get medical advice on a pressure sore

Sometimes you can do everything in your power to prevent a pressure sore yet still develop one. Pressure sores should be treated as soon as they’re noticed. Early treatment means the sore is more likely to heal rather than get worse.

If you’re in a care home or a hospital, you should tell a nurse or carer as soon as symptoms develop. If nothing is done, the sore will get worse. These injuries typically do not heal on their own.

If you’re a carer or looking after someone who is at risk of developing pressure sores, you should contact a doctor as soon as symptoms are noticed.

Immediate medical advice should be sought if:

  • The person has swollen, red skin.
  • There is pus seeping from the pressure sore or wound.
  • The person has a rapid heartbeat but cold skin.
  • The person is in pain, or their pain has gotten worse.
  • The person has a high temperature.
Treating Pressure Sore

How is a pressure sore treated?

Typical treatments for pressure sores include changing position regularly, using special mattresses to relieve or reduce pressure, and using special dressings to promote healing. Occasionally, surgery is required.

Changing position

Just like when you’re trying to prevent pressure sores, changing position is one of the most effective treatments for the condition. Regular movement helps relieve pressure on the sores that have developed.

Some people might need to be moved as frequently as every fifteen minutes while others might only need repositioning every two or four hours.

People might also be taught how to lie and sit in better positions, how to adjust themselves in their bed or chair, and how to support their feet.

Mattresses and cushions

For mild sores, you might need a dynamic or static foam mattress. With more serious pressure ulcers, it’s likely you’ll need a sophisticated bed system that uses an air mattress to provide relief to different areas of the body.

Pressure-redistributing cushions are also available too.


Specialist dressings can be applied to pressure wounds to protect them and speed up healing. Types of dressings available include:

  • Alginate dressings – these contain calcium and sodium and are made from seaweed. The calcium and sodium help to speed up healing.
  • Hydrocolloid dressings – these contain a special gel that encourages new skin cells to grow. They also keep the skin around the ulcer dry.
  • Other dressings – there are other specialist dressings like films, foams, gelling fibres, hydrofibres, and antimicrobial dressings that are used to treat pressure sores.

Creams and ointments

Topical ointments and creams like antimicrobial or antiseptic creams aren’t typically recommended for pressure sores. Barrier creams, however, are useful to protect skin that has been irritated or damaged by incontinence. This is to protect the skin from sores developing.


If there is an infected pressure sore, antibiotics will be prescribed.

Untreated infections leave the patient at risk of serious infections like sepsis (blood poisoning), cellulitis (bacterial infection of the tissues underneath the skin), and osteomyelitis (bone infections).

Diet and nutrition

Though diet and nutrition isn’t an active pressure sore treatment, a healthy diet can help to speed up how quickly a pressure sore heals. Hydration is also vital in this process too.

Removing damaged tissue (debridement)

Sometimes, it is necessary to carry out a process called debridement. This means that dead tissue in the pressure sore is removed to promote healing. When the dead tissue is small, special dressings are used to remove it.

When the amount of dead tissue is larger, there are other techniques for removing it. These include high-pressure water jets, ultrasound, and surgical instruments like forceps and scalpels.

Before debridement, a local anaesthetic will be used to numb the area. Pain management is also important after the procedure.


Sometimes it is necessary to have surgery to treat severe pressure sores. The surgery will help seal wounds, speed up the healing process and minimise a person’s infection risk.

Surgical treatment will typically involve:

  • Cleaning the pressure sore and closing it up by bringing its edges together.
  • Cleaning the pressure sore and closing it up by using healthy skin tissue from another part of the body.

The surgery to treat pressure wounds isn’t easy and it is made more difficult because often those experiencing pressure sores already have poor health.

Surgery does come with some risks. These include the implanted skin dying, sepsis, osteomyelitis, DVT (deep vein thrombosis), and abscesses.

Final thoughts

As we’ve seen, pressure sores are notoriously difficult to heal. For this reason, preventing their occurrence should be an important part of any patient’s care plan when they are deemed at risk. Recognising the early signs is also important as treatment is easier when the sores are noticed quickly.

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About the author

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Louise Woffindin

Louise is a writer and translator from Sheffield. Before turning to writing, she worked as a secondary school language teacher. Outside of work, she is a keen runner and also enjoys reading and walking her dog Chaos.

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