Tenormin Tab 25mg contains the active ingredient atenolol, a selective beta-blocker used to manage hypertension (high blood pressure), and angina (chest pain), and to improve survival after a heart attack. Each tablet contains 25mg of atenolol, which works by blocking beta-adrenergic receptors in the heart, reducing heart rate, cardiac output, and the workload on the heart. This action helps lower blood pressure and lessen chest pain. This medication can be trusted to effectively provide relief to those suffering from angina and hypertension, however, these tablets should not be used without a prescription.