Even with the best possible medical care, complications can arise from grade three or grade four pressure ulcers and can occasionally be life-threatening.

These complications are discussed below.

Cellulitis

Infection can spread from the site of the pressure ulcer to a deeper layer of skin. This type of infection is called cellulitis. It causes symptoms of pain and redness, plus swelling of the skin. It will need to be treated with a course of antibiotics.

Read more information about cellulitis.

Left untreated, there is a risk that the infection can spread to the blood (see below) or the underlying bone or joint. In rare cases, where pressure ulcers involve the lower back, tail bone and spine, the pressure ulcer can spread to the membranes that surround the spine and brain. This is known as meningitis.

Blood poisoning

If a person with a weak immune system has a pressure ulcer that becomes infected, there is a risk that the infection will spread into their blood and other organs. This is known as blood poisoning or septicaemia.

In the most serious cases of blood poisoning, damage to multiple organs can lead to a large drop in blood pressure, known as septic shock, which can be fatal. Symptoms include cold skin and an increased heart beat.

Blood poisoning is a medical emergency. It requires immediate treatment in an intensive care unit (ICU), so that the functions of the body can be supported while the infection is treated with antibiotics or antiviral medication.

Read more information about blood poisoning.

Bone and joint infection

Infection can also spread from a pressure ulcer into underlying joints (septic arthritis) and bones (osteomyelitis).

Both of these infections can damage the cartilage, tissue and bone. They may also affect the joints and limbs.

Antibiotics are required to treat bone and joint infections. In the most serious of cases, infected bones and joints may need to be surgically removed.

Necrotising fasciitis

Necrotising fasciitis, commonly known as "flesh-eating" bacteria, is a serious skin infection that causes rapid tissue death. It can occur when a pressure ulcer becomes infected with a particular type of bacteria, such as Group A streptococci.

Emergency treatment is required. It involves a combination of antibiotics and surgical debridement of the dead tissue.

Gas gangrene

Gas gangrene is a serious but rare form of infection that occurs when a pressure ulcer becomes infected with the clostridium bacteria. The bacteria thrive in environments where there is little or no oxygen. They produce gases and release dangerous toxins. Symptoms of gas gangrene include severe pain and rapid swelling of the skin.

Gas gangrene requires immediate treatment with surgical debridement. In the most serious of cases, it may be necessary to amputate the affected body part to prevent the gangrene from spreading to the rest of the body.

Read more about gangrene.