Long-term use of isosorbide mononitrate may have the side effect of generalized vasodilation. The more typical side effects of isosorbide mononitrate are rare when taken in the right doses over a long period of time, and the side effects tend to occur initially and gradually disappear with continued use. However, if isosorbide mononitrate is taken in excess over a long period of time, it can cause a generalized vasodilatation of the blood vessels. Isosorbide mononitrate can dilate peripheral arterial and venous blood vessels, reducing the amount of return blood while lowering the anterior and posterior load on the heart. If patients take isosorbide mononitrate for a long period of time, the side effects of headache and hypotensive reactions may occur. 1. Headache: If long-term overdose of isosorbide mononitrate is taken, side effects characterized by wave-like headache may occur, which may also be accompanied by facial flushing, vertigo and other clinical manifestations. 2. Hypotensive reaction: If long-term overdose of isosorbide mononitrate, peripheral vasodilatation is obvious, there may be dizziness, black eyes, fatigue, sweating, panic as the main feature of the hypotensive reaction. At this time, blood pressure should be measured immediately to assist in the diagnosis, if necessary, temporary suspension of the drug to the cardiovascular department for adjustment of medication.