Zestril is a prescription medication containing 5mg lisinopril dihydrate, which is equivalent to 5mg anhydrous lisinopril. It is manufactured by AstraZeneca and comes in a pack of 28 tablets. This medication belongs to a class of drugs called ACE inhibitors used to treat high blood pressure and heart conditions. This medication should not be used during pregnancy. The active ingredient lisinopril works by relaxing blood vessels to lower blood pressure and improve blood flow. Each tablet contains 5mg of lisinopril dihydrate. The medication requires a prescription and should only be taken under medical supervision. Patients should carefully read the included leaflet and consult their doctor for complete usage instructions and safety information.