 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  different dosing. Tell your doctor if this medication stops working well (for example, you have more frequent or worsening chest pain).The side effects of Isosorbide Mononitrate Oral: Headache, dizziness, lightheadedness, nausea, and flushing may occur as your body adjusts to this medication. If any of these effects last or get worse, tell your doctor or pharmacist promptly. Headache is often a sign that this medication is working. Your doctor may recommend treating headaches with an over-the-counter pain reliever (such as acetaminophen, aspirin). If headaches continue or become severe, tell your doctor promptly. To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. An empty tablet shell may appear in your stool. This effect is harmless since your body has already absorbed the medication. Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: fainting, fast/irregular/pounding heartbeat. A very serious allergic reaction to this drug is rare. </s>