The amount of time it takes to heal a wound is variable and depends upon several factors. These include the cause and size of the wound, nutritional status of the patient and their overall medical condition. Decreased blood flow can play a critical role in how fast a wound heals. The presence of active smoking, uncontrolled diabetes, persistent pressure, infection or cancer in the wound, along with the patient's environment and current wound-dressing regimen, can impair the process of healing. However, in an otherwise healthy patient, a wound should be completely healed or show significant signs of healing within four weeks.