Gangrene

Tissue dying from loss of blood supply or infection. Always an emergency, and in gas gangrene it is measured in hours.

What it is

Death of body tissue, usually from loss of blood supply, from serious infection, or from both.

**Dry gangrene** develops slowly, usually in the toes and feet, from peripheral arterial disease or diabetes. The tissue becomes cold, dry, and black, with a clear line between dead and living tissue.

**Wet gangrene** involves infection, is swollen, blistered and foul-smelling, and spreads quickly.

**Gas gangrene** and necrotising fasciitis are the fastest and most dangerous forms, spreading through tissue within hours, with pain out of all proportion to how the skin looks. Survival depends on immediate surgery and antibiotics.

The route in is usually unremarkable: a small foot wound, a pressure sore, a burn, an injection site, or surgery. In people with neuropathy the initial injury is painless and unnoticed, which is why daily foot checks in diabetes are not a formality.

Treatment is removing the dead tissue, treating the infection, and restoring blood supply where possible. Amputation is sometimes necessary and is more likely the later it presents.

Almost all of it in the UK is preventable, through foot care, wound care and pressure area care.

Signs you might notice

Skin turning red, then purple, bronze, blue or black.

Coldness and numbness in the affected part, or severe pain that then disappears as the nerves die.

A clear line between healthy and affected tissue.

Swelling, blisters, discharge, and a foul smell.

Crackling under the skin, which suggests gas in the tissue.

Fever, fast heart rate, confusion, feeling very unwell. See sepsis.

999 immediately for: any black or dusky area of skin; severe pain out of proportion to the appearance; rapidly spreading redness; skin crackling; or fever with any wound.

Urgent, the same day: any wound on a diabetic foot; a foot that is cold, pale or painful at rest.

How it can affect day-to-day life

The prevention is entirely in daily routine: looking at feet, relieving pressure, dressing wounds, and getting redness seen early.

In pressure ulcers, tissue death happens under intact skin before anything is visible, which is why a persistently red or purple area that does not blanch is already an emergency of its own kind.

Pain that disappears is not improvement. In a limb that was painful and has gone numb, the nerves may have died, and that is a deterioration.

People with neuropathy will not feel any of the early warning, so the checking has to be done by somebody else and has to be part of the routine, not a response to complaint.

After treatment, rehabilitation, prosthetics and psychological support all matter, and the emotional impact of losing part of a limb is often left unaddressed.

Supporting someone well

Look at feet and pressure areas daily in anyone at risk, and act on redness rather than waiting for a wound.

Treat any break in the skin on a diabetic foot as urgent, the same day.

Call 999 for black or dusky skin, severe disproportionate pain, rapidly spreading redness or crackling skin.

Do not apply heat, and do not attempt to remove dead tissue at home.

Relieve pressure immediately: reposition, offload the heel, check footwear for anything inside.

Stop smoking; it directly worsens the circulation this depends on.

Optimise glucose control and get vascular assessment for anyone with poor circulation.

After surgery or amputation, ask for prosthetics, physiotherapy and psychological support.

Where to get help

999 or A and E immediately for any suspected gangrene.

The vascular, diabetes foot or tissue viability team for ongoing care.

A GP or podiatry service the same day for any diabetic foot wound.

Diabetes UK on 0345 123 2399, and Circulation Foundation for vascular disease.