There isn’t a simple “emergency” or “not an emergency” label for a foot ulcer. Instead, certain findings come with a timeframe, and that’s more useful to know than a label would be.
Call your health care provider right away if you have a cut, blister, or bruise on your foot that does not start to heal after a few days; skin on your foot that becomes red, warm, or painful, which are signs of a possible infection; a callus with dried blood inside of it, which often can be the first sign of a wound under the callus; or a foot infection that becomes black and smelly, which are signs you might have gangrene.
If a foot ulcer is already being treated, contact your provider if you have any of these signs and symptoms of infection: redness, increased warmth, or swelling around the wound; extra drainage; pus; odor; fever or chills; increased pain; or increased firmness around the wound. Also contact your provider if your foot ulcer is very white, blue, or black.
With leg ulcers, contact a doctor or nurse quickly for sudden, severe pain in the leg or foot; a foot or toes that become very cold, pale, blue, or black; rapidly spreading redness, swelling, or fever; black tissue in the wound; or new loss of feeling or sudden numbness. These may mean a serious problem with blood flow or infection and need urgent medical assessment.
One more point matters here. In people with diabetes or pressure ulcers, infection may sometimes cause less obvious redness but more pain, swelling, or general illness. So a foot ulcer that looks unremarkable is not, for that reason alone, reassuring.
One condition is called a life-threatening medical emergency: sepsis, the body’s overactive and extreme response to an infection. Anyone with an infection could get sepsis. Its symptoms affect the whole body: rapid breathing and heart rate, shortness of breath, confusion or disorientation, extreme pain or discomfort, fever, shivering, or feeling very cold, and clammy or sweaty skin.