Blood infection in the leg: what to know

A cut, ulcer, bite or cracked skin can let bacteria enter the tissues. Cellulitis is a common leg infection that causes spreading redness, warmth, swelling and tenderness. If infection enters the bloodstream, the body can respond with fever, shivering, fast breathing, a racing heartbeat, marked weakness or confusion. Fever can occur with many infections, including respiratory conditions, so the leg findings and overall condition matter.

A red area that is expanding, increasing pain, pus or red streaks travelling up the leg suggests that infection needs prompt clinical review. People with diabetes, poor circulation or reduced immunity should seek advice early for a new wound or skin change.

Have a painful, warm or spreading leg rash assessed promptly. Keep any wound clean and covered, avoid squeezing it, and mark the edge of redness with a pen so you can notice spread. Rest the leg in a comfortable position and drink fluids if you can. A clinician may prescribe treatment after examining the skin; do not use leftover antibiotics or share medication.

Call emergency services for confusion, faintness, difficulty breathing, very fast breathing, blue or mottled skin, severe weakness, uncontrollable shivering or rapidly worsening pain and swelling. Emergency assessment is also needed if the leg becomes numb, cold or unusually pale, or if a wound turns dark.

Ask whether the infection is limited to the skin or may be deeper, how to care for the wound, which medicine is suitable, and how soon improvement should begin. Ask which changes mean you should return urgently.