Before taking atenolol, tell your doctor or pharmacist if you are allergic to it; or to other beta-blockers (e.g., metoprolol, propranolol) ; or if you have any other allergies.
This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: certain types of irregular heartbeats (e.g., sinus bradycardia, second or third degree atrioventricular block), cardiogenic shock, severe heart failure (overt or decompensated type), a certain type of tumor (untreated pheochromocytoma).
Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart failure (treated, compensated type), breathing problems (e.g., asthma, chronic obstructive lung disease), diabetes, overactive thyroid disease (hyperthyroidism), kidney disease, blood circulation problems (e.g., Raynaud's disease), mental/mood disorders (e.g., depression), certain muscle disease (myasthenia gravis).
Before having surgery, tell your doctor or dentist that you are taking this medication.
If you have diabetes, this medication may mask the fast/pounding heartbeat you would usually feel when your blood sugar level falls too low (hypoglycemia). Other symptoms of a low blood sugar level such as dizziness or sweating are unaffected by this drug.
This drug may make you dizzy or drowsy; use caution engaging in activities requiring alertness such as driving or using machinery. Limit alcoholic beverages.
To minimize dizziness and lightheadedness, get up slowly when rising from a seated or lying position.
This drug should be used only when clearly needed during pregnancy. Discuss the risks (e.g., low birth weight) and benefits with your doctor.
This drug passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breast-feeding. (source:webmd.com)