Curad advises that healing occurs in four stages with deep cuts: hemostatis, which occurs immediately; inflammation, which lasts up to 4 days; proliferation, which typically takes 21 days; and remodeling, which can take up to 2 years.
A 2010 study published by the National Institute of Health found that the following factors can affect proper wound healing: oxygenation, infection, age and sex hormones, stress, diabetes, obesity, medications, alcoholism, smoking and nutrition. The NIH also found that between 3 and 6 million people suffer from non-healing wounds, with the majority of those being people over 65 years of age.
Inova.org defines a non-healing wound as one that has not healed within 4 to 6 weeks. The symptoms of a non-healing wound include pain and redness, oozing and an odor from the wound. Non-healing wounds put people at risk for infection, so anyone who shows symptoms of a non-healing wound should seek medical care immediately.