Metoprolol is a commonly prescribed beta-blocker used to treat conditions such as high blood pressure, angina, certain heart-rhythm problems, and heart failure. It may also be prescribed after a heart attack to improve survival. The medication works partly by slowing the heart rate and reducing the workload on the heart.
Although metoprolol can be an important part of heart treatment, it can cause side effects. Some are mild and may improve as your body adjusts to the medication, while others require prompt medical attention.
Here are 10 important side effects to know about.
1. Tiredness or Fatigue
Feeling unusually tired is one of the more commonly reported effects of metoprolol. Because the medicine slows the heart rate and reduces the heart’s workload, some people may feel less energetic, particularly when starting treatment or after a dose increase.
If fatigue is severe, persistent, or interferes with normal daily activities, speak with your doctor rather than changing the dose yourself.
2. Dizziness or Lightheadedness
Metoprolol can cause dizziness or lightheadedness, particularly when blood pressure falls or when you stand up quickly. Clinical information lists dizziness among the common adverse effects.
Move slowly when getting out of bed or standing from a chair. If you repeatedly feel as though you might faint, contact your healthcare professional.
3. Slow Heartbeat
Because metoprolol is designed to slow the heart rate, some reduction in heart rate is expected. However, a heart rate that becomes excessively slow can cause weakness, dizziness, fainting, or other symptoms.
A very slow or irregular heartbeat should be discussed promptly with a healthcare professional.
4. Low Blood Pressure
Metoprolol can lower blood pressure. For some people this is part of the desired therapeutic effect, but blood pressure that becomes too low may cause dizziness, weakness, blurred vision, or fainting.
If you regularly experience these symptoms, your doctor may need to review your medication and blood-pressure readings.
5. Shortness of Breath
Shortness of breath has been reported in people taking metoprolol.
However, breathing difficulty should not automatically be assumed to be a medication side effect. It can also indicate an underlying heart or lung problem. New, severe, or rapidly worsening breathing difficulty requires prompt medical evaluation.
6. Diarrhea and Other Digestive Problems
Digestive effects can occur with metoprolol. Diarrhea is among the reported adverse reactions, while nausea, stomach discomfort, constipation, gas, and heartburn have also been reported.
If diarrhea or vomiting is severe or persistent, contact your healthcare professional, particularly if you are unable to drink enough fluids.
7. Cold Hands and Feet
Some people taking metoprolol may notice that their hands or feet feel colder than usual. This effect is listed among the cardiovascular adverse reactions associated with metoprolol.
Persistent or severe changes in circulation should be reported to your doctor, especially if you already have circulation problems.
8. Sleep Problems, Headache, or Vivid Dreams
Some people may experience headache, difficulty sleeping, nightmares, or other sleep-related changes while taking metoprolol.
These symptoms aren’t experienced by everyone, but if they become troublesome, discuss them with your healthcare provider.
9. Depression or Changes in Mood
Depression has been reported among people taking metoprolol. Official prescribing information also lists mental confusion and short-term memory problems among reported reactions.
If you notice significant changes in mood, concentration, memory, or emotional well-being after starting the medication, tell your doctor.
10. Swelling, Fainting, or Rapid/Irregular Heartbeat
Some symptoms require more urgent attention. MedlinePlus advises seeking medical help for symptoms such as fainting, swelling of the hands, feet, ankles, or lower legs, rapid or pounding heartbeat, irregular heartbeat, or difficulty breathing.
These symptoms can sometimes indicate a more serious cardiovascular problem and should not simply be ignored.
An Important Warning: Don’t Stop Metoprolol Suddenly
One of the most important things to remember is that you should not suddenly stop taking metoprolol unless your healthcare professional specifically tells you to do so.
Abruptly stopping metoprolol can worsen heart-related problems, and official prescribing information warns that sudden withdrawal may worsen myocardial ischemia.
If you think metoprolol is causing side effects, contact your doctor. Your healthcare provider can decide whether the dose should be adjusted or whether another treatment is more appropriate.
Metoprolol Can Also Affect Low Blood Sugar Warning Signs
People with diabetes should be particularly careful. Metoprolol can increase the risk of hypoglycemia and may mask some warning symptoms of low blood sugar, such as a fast heartbeat.
This does not mean people with diabetes cannot take metoprolol, but their healthcare team may recommend closer monitoring.
When Should You Seek Medical Help?
Seek urgent medical attention for severe difficulty breathing, fainting, significant swelling, or a rapid, pounding, or irregular heartbeat.
For milder symptoms such as tiredness, dizziness, or digestive problems, speak with your doctor or pharmacist if they are persistent or interfering with your daily life.
Final Thoughts
Metoprolol can be an effective medication for many heart and blood-pressure conditions, but like all prescription medicines, it can cause side effects.
Knowing what to watch for can help you recognize problems early. Most importantly, never change your dose or stop metoprolol on your own. If you are experiencing side effects, discuss them with the healthcare professional who prescribed the medication.