Atenolol is used with or without other medications to treat high blood pressure (hypertension). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. This medication is also used to treat chest pain (angina) and to improve survival after a heart attack. Atenolol belongs to a class of drugs known as beta blockers. It works by blocking the action of certain natural chemicals in your body, such as epinephrine, on the heart and blood vessels. This effect lowers the heart rate, blood pressure, and strain on the heart.

See also Warning section. Take this medication by mouth with or without food as directed by your doctor, usually 1 to 2 times daily. The dosage is based on your medical condition and response to treatment. Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time(s) each day. It is important to continue taking this medication even if you feel well. Most people with high blood pressure do not feel sick. If this product is used for chest pain, it must be taken regularly to be effective. It should not be used to treat chest pain when it occurs. Use other medications (such as nitroglycerin placed under the tongue) to relieve chest pain as directed by your doctor. It may take 1 to 2 weeks before you get the full benefit of this medication. Tell your doctor if your condition does not improve or if it worsens (for example, if your blood pressure readings remain high or increase, if your chest pain occurs more often).

Before taking atenolol, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: certain types of heart rhythm problems (such as slow heartbeat, second- or third-degree atrioventricular block), breathing problems (such as asthma, chronic bronchitis, emphysema), blood circulation problems (such as Raynaud's disease, peripheral vascular disease), kidney disease, serious allergic reactions including those needing treatment with epinephrine, a certain muscle disease (myasthenia gravis). This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages. Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). If you have diabetes, this product may prevent the fast/pounding heartbeat you would usually feel when your blood sugar level falls too low (hypoglycemia). Other symptoms of low blood sugar, such as dizziness and sweating, are unaffected by this drug. This product may also make it harder to control your blood sugar levels. Check your blood sugar levels regularly as directed by your doctor. Tell your doctor immediately if you have symptoms of high blood sugar such as increased thirst/urination. Your doctor may need to adjust your diabetes medication, exercise program, or diet. This medication is not recommended for use during pregnancy. It may harm an unborn baby. Consult your doctor for more details. This medication passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breast-feeding.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

See also Warning and Precautions sections. Dizziness, lightheadedness, tiredness, and nausea may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. This drug may reduce blood flow to your hands and feet, causing them to feel cold. Smoking may worsen this effect. Dress warmly and avoid tobacco use. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if any of these unlikely but serious side effects occur: very slow heartbeat, severe dizziness, fainting, trouble breathing, blue fingers/toes, mental/mood changes (such as confusion, mood swings, depression). Although this medication may be used to treat heart failure, some people may rarely develop new or worsening symptoms of heart failure. Tell your doctor right away if you experience any of these unlikely but serious side effects: swelling ankles/feet, severe tiredness, shortness of breath, unexplained/sudden weight gain. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any of the following symptoms of a serious allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details.