It’s more accurate to say smoking makes an arterial wound harder to heal than to say it stops healing outright. The difference is worth keeping, because overstating it is the quickest way to make advice easy to dismiss.
Smoking comes up twice for ischemic ulcers, the wounds also called arterial ulcers. It’s one of the conditions that can cause ischemic wounds. And one of the lifestyle changes for these wounds is: Quit smoking. Smoking can lead to narrowed arteries.
Narrowed arteries are not a side detail here. They are the most common cause of ischemic ulcers. They prevent a healthy supply of blood from flowing to the legs, and as a result the tissues in your legs do not get enough nutrients and oxygen. So the thing smoking can lead to is the same thing that usually causes the wound.
If you have a wound, taking these lifestyle steps can improve blood flow and aid healing. Quitting can still help after the wound exists, not only as prevention.
Smoking matters for healing in other settings too. It’s one of the factors that can prevent wounds from healing or slow the process. It can delay healing after surgery and increases the risk for complications such as infection and wounds breaking open. For people with diabetes, smoking decreases blood flow to the feet.
There’s no set number for how much smoking slows healing. What is consistent is the direction: less blood reaching the tissue, and healing made harder.