Why does nicotine cause necroses?

Nicotine does not cause necrosis. Nicotine is the addictive drug found in tobacco products, such as cigarettes and cigars. It is a stimulant that can cause an increased heart rate, elevated blood pressure, and other cardiovascular effects. Nicotine can also cause constriction of blood vessels, which can lead to tissue hypoxia and, in severe cases, necrosis. However, nicotine itself does not directly cause necrosis.