The most common side effects of isosorbide nitrate include headache, increased heart rate, facial flushing and low blood pressure. Nitrate drugs are used to treat coronary heart disease by dilating blood vessels and improving coronary artery blood supply. But it also dilates the blood vessels in the brain, so it can cause the side effect of headache, which will gradually reduce or disappear during the process of insisting on the medication. When taking nitrates, also note that blood pressure must be measured, if the blood pressure is below 90/60mmHg, then it is not recommended to apply this type of drugs. In addition, the application of nitrates is not recommended for patients with glaucoma or constrictive pericarditis, shock, etc., because this drug may aggravate the symptoms of these diseases or may be dangerous.