Cellulitis

A bacterial infection spreading through the skin and the tissue beneath it. Common, and it turns serious fast.

What it is

Cellulitis is a bacterial infection of the deeper layers of skin. It usually affects the lower leg, and it usually starts at a break in the skin so small that nobody noticed it: a crack between the toes from athlete's foot, an insect bite, a scratch.

It accounts for a substantial number of hospital admissions each year, and in people with lymphoedema, diabetes or venous leg ulcers it recurs repeatedly.

Untreated it spreads, and it can lead to sepsis. That is why redness spreading up a leg is an urgent matter rather than a wait-and-see one.

Signs you might notice

Skin that is red or discoloured, hot, swollen and tender, with a poorly defined edge that expands.

On darker skin, redness is much harder to see. Heat, swelling, tightness and pain are the more reliable signs, and cellulitis is under-diagnosed in people with darker skin for exactly this reason.

Feeling unwell, feverish, shivery.

Blistering, or skin that looks like orange peel.

Red streaks tracking up the limb, or confusion in an older person: both mean go now.

How it can affect day-to-day life

Recurrence is the pattern that wears people down. Each episode damages lymphatic drainage further, which makes the next one likelier, which is why people with lymphoedema get caught in a cycle.

The commonest missed cause is the humble one: untreated athlete's foot providing the entry point, episode after episode.

It is also over-diagnosed. Both legs red and swollen is rarely cellulitis, which is almost always one-sided; that picture is usually venous eczema or lymphoedema, and antibiotics will not help it.

Supporting someone well

Draw round the edge with a pen and write the time. It is the simplest and most useful thing anybody can do, because it turns "is it spreading" from an opinion into an observation.

Treat athlete's foot properly and keep the skin between toes dry. This prevents more recurrences than anything else.

Moisturise daily. Intact skin is the barrier.

Elevate the limb and keep taking the full course of antibiotics.

For recurrent cellulitis, ask about preventive antibiotics and about a lymphoedema assessment. Both exist and both are under-offered.

In a service, record and escalate spreading redness rather than filing it as a skin observation. Fiducia Together keeps skin integrity with the observations, so a spreading area and a rising temperature are seen together.

Where to get help

A GP or urgent treatment centre for antibiotics, same day.

Go to A and E for spreading redness with fever, confusion, vomiting, or if the person is very unwell.

Severe pain out of proportion to the appearance, with rapidly spreading discolouration, is a surgical emergency.