Before taking metoprolol, tell your doctor or pharmacist if you are allergic to it; or to other beta-blockers (such as atenolol, propranolol); 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 a slow heartbeat, second- or third-degree atrioventricular block, sick sinus syndrome), breathing problems (such as asthma, chronic bronchitis, emphysema), liver disease, serious allergic reactions, including those needing treatment with epinephrine, blood circulation problems (such as Raynaud's disease, peripheral vascular disease), mental/mood disorders (such as depression), a certain muscle disease (myasthenia gravis).

This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit or avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

This product may prevent the fast/pounding heartbeat you would usually feel when your blood sugar level falls too low (hypoglycemia). The risk is higher if you have diabetes, or are vomiting, fasting, or not eating regularly. Other symptoms of low blood sugar level, such as dizziness and sweating, are not affected by this drug.

If you have diabetes, this product may make it harder to control your blood sugar levels. Check your blood sugar levels regularly as directed by your doctor. Tell your doctor right away 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.

Children may be at greater risk for low blood sugar (hypoglycemia) while using this drug, especially if they are vomiting or not eating regularly. To help prevent low blood sugar, make sure children eat regularly. If your child cannot eat regularly, is vomiting, or has symptoms of low blood sugar (such as sweating, shaking), tell the doctor right away.

During pregnancy, this medication should be used only when clearly needed. It may harm an unborn baby. Discuss the risks and benefits with your doctor.

This drug passes into breast milk but is unlikely to harm a nursing infant. Consult your doctor before breastfeeding.