Zestril 20mg (lisinopril) is a prescription medication used to treat high blood pressure, heart failure, and improve survival after heart attacks. Each pack contains 28 tablets manufactured by AstraZeneca. Lisinopril belongs to a class of drugs called ACE inhibitors that work by relaxing blood vessels. The active ingredient is lisinopril dihydrate equivalent to 20mg anhydrous lisinopril per tablet. This medication should be taken exactly as prescribed by your healthcare provider, typically once daily. It can be taken with or without food. Common side effects may include dizziness, headache, cough, and changes in blood pressure. This is a prescription-only medication that requires regular monitoring by a healthcare professional. Store at room temperature away from moisture and heat.