Metoprolol Warnings and Precautions (Cont.)

• Metoprolol can interact with certain medications (see Drug Interactions With Metoprolol).
   
• Metoprolol may hide certain signs of hyperthyroidism. Do not stop metoprolol abruptly, as this can cause serious symptoms. Make sure to talk with your healthcare provider before stopping metoprolol so that it can be done so in a safe manner.
   
• Metoprolol may cause extreme low blood pressure and/or a slow heart rate in some people. Symptoms can include dizziness, lightheadedness, and fainting. If you develop any of these symptoms, contact your healthcare provider. Extreme low blood pressure is more likely to occur in people who are taking a diuretic, who are on dialysis, or who have diarrhea or vomiting.

Also, make sure not to drive, operate any heavy machinery, or perform any other tasks that require alertness before you know how metoprolol affects you.

• Using beta blockers, such as metoprolol, for a long period of time can, in some cases, lead to heart failure. If you notice any of the following symptoms, contact your healthcare provider: unexplained weight gain; swelling of the ankles, feet, or legs; cough; and shortness of breath (see Symptoms of Congestive Heart Failure for more signs and symptoms).
   
• People with severe congestive heart failure taking metoprolol are at increased risk for worsening heart failure. This occurs more often when the dose is increased. Therefore, if your healthcare provider prescribes metoprolol because he or she believes that the benefits of metoprolol outweigh the potential risks, he or she may choose to monitor your situation more closely, especially during dosage changes. Contact your healthcare provider if you notice any congestive heart failure symptoms.
   
• People taking metoprolol should not stop it abruptly. In clinical studies, this has been shown to increase a person's chances for developing angina (chest pain), heart attack, or serious irregular heart rhythms (arrhythmias). This risk is even greater in people with existing heart disease.
   
• Beta blockers, including metoprolol, are used with caution (if even at all) in people with certain lung diseases, such as asthma, emphysema, chronic bronchitis, or chronic obstructive pulmonary disease (COPD). This is because beta blockers affect the lungs and can cause a narrowing of the airways. This risk is increased in people with certain lung diseases. If you develop problems breathing or experience wheezing, call your healthcare provider.
   
• For people with allergies, taking metoprolol may increase the reaction to the specific allergens, and your body may not respond to the usual doses of epinephrine.
   
• If you are going to have surgery, let your healthcare provider or dentist know that you are taking metoprolol.
   
• Metoprolol is a pregnancy Category C medicine, meaning that there may be an increased risk to the fetus. Let your healthcare provider know if you are pregnant or thinking of becoming pregnant. If you become pregnant while taking metoprolol, contact your healthcare provider (see Metoprolol and Pregnancy for more information).
   
• If you are breastfeeding, keep in mind that metoprolol passes through your milk. Therefore, if you are taking metoprolol, it is generally recommended to stop nursing. Talk to your healthcare provider about your particular situation.