Medically reviewed guide · Last updated: 1 September 2026 · Reading time: approx. 11 min

Poor Wound Healing: When Wounds Won't Close — Circulation, Diabetes or Medication?

The most common causes compared

The causes in detail

Wound healing runs in three overlapping phases: an inflammatory reaction cleans the wound — slight redness and swelling in the first few days are normal — then new tissue with a good blood supply (granulation tissue) fills the defect, and finally skin grows over it from the edges. All of this needs oxygen, nutrients, working immune defences and protection from pressure and germs. If any of these is missing, the wound usually gets stuck in the inflammatory phase. The underlying conditions, with all the treatment details, are covered in the articles on peripheral arterial disease (PAD), type 2 diabetes and varicose veins.

After an operation: infection, seroma and a wound that opens up

Surgical wounds have usually closed at the surface after a few days and, after one to two weeks, have healed enough for the stitches to be removed. The most common problem is wound infection: after an initial improvement, redness, warmth, swelling and pain increase again, cloudy fluid or pus comes out of the incision, and sometimes a fever develops — usually in the first days to weeks, and with implants later as well. If wound fluid (seroma) or blood (haematoma) collects under the stitches, it creates tension and pushes the edges apart; if they come apart, specialists call it wound dehiscence. Smoking, excess weight, poorly controlled diabetes, malnutrition and treatment with cortisone or immunosuppressants increase the risk. First step: call the hospital or practice that operated on you the same day, and do not interfere with the stitches yourself.

Weak veins: the "open leg" (venous leg ulcer)

The venous leg ulcer is the most common cause of chronic leg wounds. If the valves in the veins no longer close properly — with varicose veins or after a thrombosis — blood pools in the legs and damages the skin over the years. Early warning signs are ankles that swell in the evening, heavy legs, brownish, hardened skin and itchy eczema around the inner ankle. Even a small injury there can turn into a weeping ulcer. The most important treatment is compression — but only once poor arterial circulation has been ruled out, because pressure on a leg with a poor blood supply can do harm.

Poor circulation in the leg arteries (PAD)

In PAD, the leg arteries are narrowed by atherosclerosis. Early on it shows up as calf pain when walking that eases when you stand still (intermittent claudication, known in German as "window-shopping disease"). Later the feet hurt at night when lying down, and even pressure from a shoe or a nail corner cut too deep no longer heals. The wounds sit on the toes, heel or edge of the foot, look punched out and are very painful; the skin around them is pale and cool. Dressings alone are not enough here: healing usually only succeeds once the blood supply is improved by a catheter procedure or a bypass — so get to vascular medicine (angiology) or vascular surgery quickly.

Diabetes: diabetic foot syndrome

Persistently high blood sugar damages the nerves (polyneuropathy), so pressure points or a small stone in your shoe are no longer felt. Often the arteries are narrowed as well and the immune defences weakened. This leads to ulcers that hardly hurt on the ball of the foot, big toe, heel or under calluses, and an infection can spread unnoticed into tendons and bone. The specialist societies advise having every new foot wound seen by a doctor promptly if you have diabetes, ideally at a specialist diabetic foot clinic. The core of treatment is taking the pressure off with special shoes or offloading dressings. A warm, swollen, reddened foot without a wound and with little pain can point to Charcot foot, in which the bones of the foot break down — this, too, is a reason to be seen quickly.

Pressure: pressure ulcers in people who are bedridden

Anyone who lies or sits for a long time without changing position squeezes off the blood supply to the skin over the sacrum, tailbone, heels or hips. A pressure ulcer (decubitus ulcer) starts as redness that no longer turns white when pressed with a finger, and can become deep within days. People at risk are those who have had a stroke or who live with paralysis, advanced dementia, incontinence or heavy sedation. What matters is regular repositioning, pressure-distributing mattresses and cushions, skin care and adequate nutrition.

Smoking, nutrition, age: the silent brakes

Smoking narrows the small blood vessels, and carbon monoxide displaces oxygen from the blood — after operations, wound complications are considerably more common in people who smoke. Malnutrition with too little protein, energy, vitamin C or zinc slows down tissue repair; it is common in older and chronically ill people and also occurs in people with excess weight. On top of this come thinner skin in older age, swelling (oedema), reduced kidney function, anaemia and alcohol.

Rare but important: skin cancer and inflammatory ulcers

Not every spot that fails to heal is an ordinary wound. Basal cell carcinoma and squamous cell carcinoma, the forms of non-melanoma skin cancer, often show up as a spot with no clear cause that bleeds again and again, crusts over and does not heal — usually on the face, ears, scalp or backs of the hands. If a wound does not heal despite good treatment, or looks unusual, a tissue sample is therefore part of the work-up. Rarely, inflammation of the blood vessels (vasculitis) or pyoderma gangrenosum is behind it — a very painful ulcer with a purplish edge that often occurs together with inflammatory bowel disease.

Self-tests: first clues at home

These observations do not replace a diagnosis, and a wound in someone with diabetes or poor circulation belongs in a doctor's hands regardless. But they help you recognise how things are progressing and give precise information at your appointment.

• The wound photo: photograph the wound every two to three days in similar light, with a ruler next to it. If it does not get smaller over two weeks, healing has stalled.
• The edge line: draw around an area of redness with a skin-friendly pen and note the time. If within hours it spreads well beyond the line, that points to a spreading infection — have it checked the same day.
• The location check: an inner ankle with brown, hard skin fits more with weak veins; toes, heel or edge of the foot with pale, cool skin more with PAD; the sole under a callus in someone with diabetes, with diabetic foot.
• The leg-raising test: if raising the leg eases the pain, that points more towards the veins. If the pain gets worse when the leg is raised and better when it hangs down, it points more towards poor arterial circulation.
• The finger-pressure test: in a bedridden relative, briefly press on an area of redness over a bony prominence. If the spot does not briefly turn white, a pressure ulcer may be starting.
• The foot mirror: if you have diabetes, look at the soles and the spaces between your toes every day and use a cotton wool ball to check whether you can feel a light touch. If you cannot feel it, that is a sign of nerve damage.

Warning signs: when not to wait

• Redness, swelling and warmth that spread over hours, or a red streak running towards the body
• Fever, chills or feeling severely ill together with a wound
• Pain that is far worse than the wound looks, with rapidly increasing swelling or blisters
• Black areas in the wound or a leg that suddenly turns cold, pale and numb
• With diabetes: any new wound, blister or discolouration on the foot
• A surgical wound that opens up, oozes pus, smells bad or becomes more painful again
• Bites, deep puncture wounds or heavily soiled wounds, or uncertain tetanus protection
• A spot with no obvious cause that bleeds again and again and does not heal over weeks

The treatment pathway: step by step

1. Care for it properly. Rinse fresh wounds under clean running water, use a wound antiseptic if needed and cover them cleanly. Check your tetanus protection — with deep or dirty wounds a booster may be needed sooner than after ten years (more under Vaccinations for adults).
2. Take stock after two weeks. If the wound has not become visibly smaller, it belongs in the GP practice. With diabetes, poor circulation, cortisone or immunosuppressants, do not wait that long.
3. Look for the cause. The practice asks about pre-existing conditions and medicines, checks pulses, sensation and skin and, depending on the findings, measures blood sugar, blood count, inflammation markers, kidney function and nutritional markers. A blood pressure measurement at the ankle compared with the arm (ankle-brachial index) reveals narrowed leg arteries; with diabetes, the value can be misleading because of calcified vessels.
4. Treat the cause and the wound. Compression for weak veins, better blood flow for PAD, consistent pressure relief for diabetic foot and pressure ulcers. Dead tissue is removed (debridement). Antibiotics are usually only used when there are signs of a genuine infection — bacteria on a chronic wound are normal.
5. Specialist help. If the wound does not heal, wound care centres, diabetic foot clinics, vascular medicine, vascular surgery or dermatology can take things further. Which treatment is right is always decided by the practice treating you, together with you.

The medication angle: when treatment slows healing

Cortisone: a question of dose and duration

Glucocorticoids such as prednisolone suppress the inflammatory reaction that a wound needs at the start and inhibit collagen formation. Short courses at low doses usually make little difference; at higher doses over months, wounds heal noticeably more slowly, and the skin becomes paper-thin and tears easily. Cortisone can also raise blood sugar. A longer course of treatment must not be stopped abruptly — how to do it safely is explained in the guide Stopping cortisone.

Immunosuppressants and rheumatology medicines

Particularly well known for impairing wound healing are the mTOR inhibitors sirolimus and everolimus, which are used after transplants; their summaries of product characteristics state this explicitly. Azathioprine, mycophenolate or biologics mainly increase the risk of infection. Whether they are paused before an operation is agreed between the rheumatology team or transplant centre and the surgical team. According to current recommendations, methotrexate is continued before many procedures; new ulcers in the mouth or on the skin while taking it can, however, be a sign of an overdose — in that case contact the practice the same day.

Cancer treatment and hydroxycarbamide

Chemotherapies slow down cell division and often the immune defences. Agents that inhibit blood vessel growth, such as the antibody bevacizumab and several tyrosine kinase inhibitors, list impaired wound healing as a known side effect; around operations, the oncology team sets treatment breaks. Irradiated skin can heal less well even years later. Hydroxycarbamide, which is taken long term for certain blood disorders, can cause painful lower leg ulcers, often near the ankle.

Blood thinners: not the healing, but the bleeding

Anticoagulants such as phenprocoumon, direct oral anticoagulants or antiplatelet medicines hardly slow the healing itself, but they encourage bruising under stitches that pushes the edges apart. Even so, never stop them on your own initiative; how this is planned before procedures is explained in the guide Medications before surgery. Rarely, painful, darkly discoloured areas of dead skin (skin necrosis) appear in the first days of treatment with phenprocoumon — a reason to see a doctor immediately.

Other active substances with an influence

Ankle swelling caused by calcium channel blockers such as amlodipine, by pregabalin or by glitazones such as pioglitazone can slow healing on the lower leg. For isotretinoin, the summary of product characteristics advises avoiding waxing, dermabrasion and laser treatments during treatment and for several months afterwards. And because an increased risk of amputation was observed with the SGLT2 inhibitor canagliflozin, the EMA (European Medicines Agency) recommends consistent preventive foot care for the whole group — including empagliflozin and dapagliflozin.

Painkillers: relieve, yes — mask, no

For wound pain, paracetamol or ibuprofen for a few days is often enough — without medical advice, according to the package leaflet, usually for no longer than three to four days in a row. Whether anti-inflammatory painkillers noticeably delay the healing of skin and soft tissue has not been conclusively established. Pain that increases instead of easing is a warning sign and should not simply be covered up. The painkiller comparison gives an overview.

How to prevent poor wound healing

• Go into surgery smoke-free — ideally from several weeks before a planned procedure; your GP practice can offer support.
• Check your feet every day if you have diabetes — well-fitting shoes, no walking barefoot, no sharp tools on calluses. Podiatry can be prescribed for diabetic foot syndrome.
• Take the strain off your veins — wear prescribed compression stockings, walk a lot, put your legs up from time to time.
• Avoid pressure — reposition bedridden people regularly, keep the heels free of pressure, check areas of redness over bones every day.
• Well nourished heals better — enough protein and energy, especially in older age and before operations. According to current knowledge, zinc or vitamin C supplements help mainly when a deficiency has been confirmed.

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