Necrotising fasciitis

Also called Flesh-eating bacteria, Nec fasc

Infection spreading through tissue in hours. Pain far worse than the skin looks is the sign, and surgery is the only treatment.

What it is

A rapidly spreading infection of the tissue beneath the skin, destroying it faster than antibiotics can reach it.

It is rare and it kills roughly one in five people who get it, largely because it is recognised late. The reason it is recognised late is that early on the skin looks unremarkable.

**The single most useful sign is pain out of all proportion to the appearance.** Somebody in agony from a small red patch, or from an area that looks like mild cellulitis but hurts far more than cellulitis should, is the presentation. Later signs, dusky skin, blisters, crackling, numbness, are late signs, and waiting for them costs limbs and lives.

It usually enters through something minor: a cut, an insect bite, an injection site, a surgical wound, or chickenpox lesions in a child. Sometimes no entry point is ever found.

Risk is higher with diabetes, immunosuppression, cirrhosis, obesity, injecting drug use, and recent surgery.

Treatment is emergency surgery to remove dead tissue, repeated over days, plus intravenous antibiotics and intensive care. Antibiotics alone do not work, because the blood supply carrying them has been destroyed.

Survivors are often left with large wounds, skin grafts, amputation and significant psychological trauma.

Signs you might notice

Severe pain, disproportionate to how the skin looks. This is the earliest and most reliable sign.

Redness, swelling and heat, often spreading visibly over hours rather than days.

Fever, feeling very unwell, confusion, vomiting.

Later: skin turning purple, grey or black; blisters or blood blisters; a crackling feeling under the skin; the area becoming numb, as the nerves die.

**999 immediately.** Say the words necrotising fasciitis at triage; it changes the priority and gets a surgeon involved.

Do not accept a wait-and-see or a prescription for oral antibiotics for a rapidly worsening painful skin infection.

If someone with chickenpox becomes suddenly much more unwell with a painful area, that is this until proven otherwise.

How it can affect day-to-day life

The delay is almost always in the first few hours, when the person is in severe pain and the examination findings are mild. Being taken seriously requires persistence, and family members are often the ones who insist.

Marking the edge of the redness with a pen and noting the time is a simple, powerful thing to do. Spread visible within an hour is diagnostic urgency.

Recovery is prolonged: multiple operations, weeks in hospital, extensive wound care and often reconstruction.

The psychological aftermath, including post-traumatic stress, is substantial and under-supported, both for the person and for family who watched it happen.

Survivors frequently report that nobody believed how much pain they were in.

Supporting someone well

Trust the pain. Severe pain with mild-looking skin is the warning.

Call 999 or go straight to A and E. Do not wait for a GP appointment.

Say necrotising fasciitis out loud at reception and at triage.

Mark the edge of the redness with a pen and write the time. Spread within an hour is critical information.

Do not accept oral antibiotics and a review tomorrow for a rapidly worsening painful area.

Mention any risk factor: diabetes, immunosuppression, recent surgery, chickenpox, injecting drug use.

Afterwards, ask for tissue viability, physiotherapy and psychological support; all three are usually needed and often not offered.

Where to get help

999 or A and E immediately.

The surgical and critical care teams; tissue viability and reconstructive services afterwards.

UK Sepsis Trust for the sepsis warning signs that accompany it.

Headway and the trauma charities for the psychological aftermath, alongside NHS psychology.