Tenormin 25mg tablets contain atenolol, a beta-blocker medication used to treat high blood pressure, angina (chest pain), and certain heart rhythm disorders. Each pack contains 28 tablets manufactured by AstraZeneca, with each tablet containing 25mg of the active ingredient atenolol. Tenormin works by blocking the action of certain natural substances in your body, such as epinephrine, on the heart and blood vessels. This effect reduces heart rate, blood pressure, and strain on the heart. The tablets should be taken orally as prescribed by your healthcare provider, typically once daily. This is a prescription-only medication that requires regular monitoring by a healthcare professional. Store at room temperature away from moisture and light.