Isosorbide dinitrate is a vasodilator that treats ineffective blood flow. It is used to prevent angina.

May be as-needed instead of on a dosing schedule. Only use sublingual tablet if angina attack has already begun. Stay seated when taking this medicine. Do not chew or swallow sublingual tablet. Sublingual tablets may be used within 15 minutes of an activity that may cause chest pain. Do not suddenly stop taking this medication.

Do not take ED drugs (Viagra, Cialis, etc.) while on this drug. Do not use if allergic to isosorbide mononitrate or nitroglycerin. Do not use if there are signs of a heart attack. Inform doctor of all conditions and medications, especially kidney disease, hypotension, and congestive heart failure. May reduce alertness; use caution when driving. Avoid alcohol. Avoid getting up too quickly. 

Go to emergency room if you encounter heart attack symptoms: chest pain, pain that spreads to jaw or shoulder, sweating, malaise. Seek immediate help if chest pain gets worse or lasts longer than 5 minutes, if you have an allergic reaction, lightheadedness, worsening angina, pulse that is too fast or slow, pounding heartbeats, or other serious reaction. Inform doctor if you notice increased sweating and hypotension. May cause severe headaches. Other side effects are headache and flushing.