Legs
Leg ulcers and slow-healing wounds
Open sores on the lower leg or foot, or wounds that are slow to heal, usually caused by poor circulation, raised pressure in the leg veins or diabetes — and occasionally an emergency when a wound turns black, the redness spreads with fever, or the leg becomes cold and pulseless.
Education and reference only. This explains the common causes of leg ulcers and slow-healing wounds and the warning signs that need urgent help, in plain language — it is not a diagnosis or a substitute for advice from a clinician. If you feel very unwell or are worried, seek medical help.
Quick answer
What is leg ulcers and slow-healing wounds?
A leg ulcer is a break in the skin of the lower leg or foot that fails to heal in the usual time, and it almost always reflects a problem with the blood supply or the tissues rather than the wound itself. Most leg ulcers come from raised pressure in the leg veins, which damages the skin around the ankle and lets it break down, often with swelling, brown staining and an aching, heavy leg.
- Get urgent help: Call 999 or go to A&E if a leg or foot becomes suddenly cold, pale, painful and pulseless — this can mean the blood supply is blocked. Seek urgent same-day help if a wound turns black, or if redness around it spreads quickly with fever, shivering or feeling very unwell — this can signal serious infection.
- Self-care: A leg ulcer needs proper assessment to find its cause, but good day-to-day care supports healing once a clinician has guided it.
About leg ulcers and slow-healing wounds
A leg ulcer is a break in the skin of the lower leg or foot that fails to heal in the usual time, and it almost always reflects a problem with the blood supply or the tissues rather than the wound itself. Most leg ulcers come from raised pressure in the leg veins, which damages the skin around the ankle and lets it break down, often with swelling, brown staining and an aching, heavy leg. Others come from poor arterial blood flow, where narrowed arteries starve the tissues of oxygen, producing painful ulcers and slow healing. Diabetes adds risk by reducing sensation and impairing healing, so small injuries on the foot go unnoticed and worsen. These ulcers can be persistent and prone to infection, and they need proper assessment to find the cause. Certain features — a wound turning black, spreading redness with fever, or a cold, pale, pulseless leg — are emergencies.
When to get help
Call 999 or go to A&E if leg ulcers and slow-healing wounds comes with any of these warning signs:
- Call 999 or go to A&E if a leg or foot becomes suddenly cold, pale, painful and pulseless — this can mean the blood supply is blocked.
- Seek urgent same-day help if a wound turns black, or if redness around it spreads quickly with fever, shivering or feeling very unwell — this can signal serious infection.
- Get urgent help for an ulcer with increasing pain, swelling, pus, an offensive smell or red streaks spreading up the leg.
- Seek same-day advice if you have diabetes and notice a new foot ulcer, breakdown or spreading redness, as foot infections can escalate fast.
- Seek urgent help if you feel feverish and generally very unwell with a leg wound, as the infection may be entering the bloodstream.
When to see a doctor
Any leg ulcer or wound on the lower leg or foot that has not healed within about two weeks should be assessed by a doctor or nurse, as it needs the cause identified and the right treatment to heal and stay healed. Seek same-day help if you have diabetes and develop any new foot ulcer or breakdown, since these can deteriorate quickly. Treat as an emergency a leg or foot that suddenly becomes cold, pale, painful and pulseless, a wound that turns black, or spreading redness with fever and feeling very unwell — these point to a blocked blood supply or serious infection and need urgent care.
Not sure how urgent it is? It is always OK to call NHS 111 for advice, day or night.
What can cause it
Common causes of leg ulcers and slow-healing wounds
Leg ulcers and slow-healing wounds has many possible causes. Each links to a full, plain-language guide to that condition — what it is, how it's treated and when to seek help.
What helps
Self-care and what you can do
A leg ulcer needs proper assessment to find its cause, but good day-to-day care supports healing once a clinician has guided it. Keep the wound and surrounding skin clean and follow any dressing advice you have been given, and try not to knock or scratch the area. If the cause is venous, gentle regular walking, raising the legs when resting and keeping the skin moisturised all help, and compression may be advised once arterial circulation has been checked. If you have diabetes, inspect your feet daily — using a mirror for the soles — wear well-fitting footwear, and never walk barefoot, since a small unnoticed injury can quickly worsen. Do not smoke, as it badly impairs circulation and healing. Report any new pain, spreading redness, odour or discharge promptly.
Answers
Leg ulcers and slow-healing wounds: frequently asked questions
Why won't the sore on my leg heal?
Leg ulcers usually fail to heal because of an underlying problem — raised pressure in the leg veins, poor arterial circulation or diabetes — rather than the wound itself. They need assessment to find the cause, as the right treatment is what allows them to heal.
When is a leg wound an emergency?
Treat it as an emergency if the leg or foot suddenly becomes cold, pale, painful and pulseless, if a wound turns black, or if redness spreads quickly with fever and feeling very unwell. These signal a blocked blood supply or serious, fast-spreading infection.
Why are foot wounds more dangerous with diabetes?
Diabetes can reduce sensation in the feet and slow healing, so small injuries go unnoticed and worsen into ulcers that easily become infected. That is why daily foot checks and prompt review of any new wound are so important if you have diabetes.
Can I treat a leg ulcer myself?
You can support healing with good wound and skin care and by following dressing advice, but a leg ulcer should be assessed by a clinician to find and treat the cause. Self-care alone is not enough, and any spreading redness, pus or new pain needs reporting promptly.
Sources
Where this is drawn from
- NICE CKS: Leg ulcer (venous).
- Circulation Foundation: leg ulcers.
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