Pronol-20 Tablet is a medication used to prevent angina, migraine, and manage pheochromocytoma. It works by slowing heart rate and relaxing blood vessels, reducing strain on the heart and improving blood flow. It should be taken as prescribed by a doctor and can be taken with or without food. Common side effects include tiredness, dizziness, weakness, cold fingers, stomach pain, nausea, vomiting, and diarrhea. It should not be used by those with asthma, heart conditions, kidney or liver problems, COPD, alcohol consumption, dizziness, or pregnancy or breastfeeding.