Nitroglycerin ointment, mainly used to reduce or relieve pain caused by anal fissures. The main ingredient of nitroglycerin ointment is nitroglycerin and the cofactor is petroleum jelly, in which nitroglycerin can directly relax the smooth muscle of blood vessels, especially the smooth muscle of small blood vessels, so that the systemic vasodilation, peripheral resistance is reduced and venous reflux is decreased, which can relieve myocardial hypoxia. Anal fissure is also caused by the spasm of the anal sphincter muscle, so nitroglycerin ointment can well relieve the spasm of the anal sphincter muscle, thus reducing the pain caused by anal fissure. However, nitroglycerin may have some adverse reactions when used, such as dizziness, nausea, rapid heartbeat, blurred vision, fatigue and a series of other adverse reactions. At the same time, nitroglycerin ointment cannot be used for people with relatively low blood pressure, insufficient blood supply to the brain, or inadequate liver and kidney function.