Metoprolol side effects: what to watch out for

Metoprolol (brand name Lopressor, Toprol, Toprol XL) is a type of medication known as a beta blocker. This class of medications decreases strain on the heart. Metoprolol is most commonly used to prevent, treat, or improve symptoms for the following conditions (Morris, 2020):

• High blood pressure (hypertension)

• Chest pain (angina)

• Heart failure

• Fast, irregular heartbeat like atrial fibrillation or atrial flutter

• Heart attack (myocardial infarction)

Metoprolol works by stopping epinephrine (also known as adrenaline) from binding to beta receptors in your heart muscle. Blocking the beta receptors allows metoprolol to decrease the workload on the heart. Metoprolol causes your heart to beat slower and squeeze less forcefully, thereby lowering blood pressure and improving chest pain.

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Metoprolol is an effective drug, but, like most medicines, it can have both mild and severe side effects.

Common side effects of metoprolol include (UpToDate, n.d.):

• Skin rash

• Itching

• Gastrointestinal problems like nausea, vomiting, diarrhea, or stomach pain

• Depression

• Dizziness

• Tiredness

• Vertigo

• Cold hands and feet

• Dry mouth

• Dry eyes and/or blurred vision

• Breathing difficulties like shortness of breath, wheezing, and cough

• Weight gain - 1.2 pounds of weight gain on average (Sharma, 2001)

• Sexual dysfunction

Black box warning from the FDA (the most serious warning they issue): Do not abruptly stop taking metoprolol without talking to your healthcare provider. Stopping metoprolol suddenly may cause chest pain or heart attack (myocardial infarction). If you need to stop metoprolol, your healthcare provider will help you decrease the dose gradually (FDA, 2006). Serious side effects of metoprolol include (UpToDate, n.d.):

• Slow heartbeat (bradycardia): One of the ways that metoprolol works is by decreasing the heart rate to lighten the load on the heart—so a somewhat lower heart rate is expected. However, some people may experience a heart rate that is too low, causing fainting spells (syncope), dizziness, chest pains, fatigue, and confusion. 

• Low blood pressure (hypotension): Metoprolol is often given to help lower blood pressure in people with high blood pressure or other heart conditions. Sometimes, the blood pressure can drop too low. Symptoms include dizziness, fainting, blurred vision, fatigue, shallow breathing, rapid pulse, and confusion. Your blood pressure may drop only after standing up from a sitting or laying down position—this is called orthostatic hypotension. Severely low blood pressure is a life-threatening emergency. 

• Worsening asthma or Metoprolol, a beta-blocker, has a small risk of triggering an asthma attack or worsening COPD by causing bronchospasm (tightening of the airways). This is because the beta receptors that line the lungs are similar to the ones that metoprolol targets in the heart and blood vessels. However, metoprolol is less likely to cause breathing issues than some of the other beta blocker drugs.

• Masking of When your blood sugar drops too low, your body gives you signals to let you know so that you can replenish your glucose reserves—these signals typically include shakiness, anxiety, confusion, rapid heartbeat (palpitations), lightheadedness, etc. However, metoprolol may mask these signs, preventing you from realizing that your blood sugars are too low. Keeping your blood sugars too low for too long can lead to seizures, unconsciousness, and even death in rare cases.

• Heart block: Metoprolol can interfere with the normal electrical system of the heart; this can lead to heart block, which causes an irregular heartbeat.

• Worsening of heart failure: People with heart failure who are taking metoprolol may notice a worsening of their heart failure symptoms; this may be especially true for women (DailyMed, 2018). An American Heart Association journal reported that women who are taking beta blockers (like metoprolol) have a higher risk of heart failure during an acute coronary syndrome (ACS) than men (Bugiardini, 2020).

This list does not include all possible side effects and others may exist. Check with your pharmacist or healthcare provider for more information.

Before starting metoprolol, or any other new medication, seek medical advice about potential drug interactions. Medicines that may interact with metoprolol include (DailyMed, 2018):

• Monoamine oxidase inhibitors (These drugs are often used to treat depression and may increase the effects of metoprolol and can potentially increase side effects. Examples include isocarboxazid, phenelzine, selegiline, and tranylcypromine.

• Epinephrine: People who take metoprolol and use epinephrine for severe allergic reactions, may find that the usual dose of epinephrine does not work as well. If you have a history of severe allergic reactions, be sure to let your healthcare provider know that you are taking a beta blocker.

• Inhibitors of the CYP2D6 system: Metoprolol is broken down by the CYP2D6 system in the liver. Drugs that interfere with the CYP2D6 system prevent metoprolol from being metabolized. As a result, you can have double the typical amounts of metoprolol circulating in your bloodstream; this increases your risk of side effects. Examples of these medications include quinidine, fluoxetine, paroxetine, and propafenone.

• Medications that slow the heart rate: Since metoprolol lowers the heart rate, combining it with other drugs that also decrease the heart rate increases your risk of having a very slow heart rate (bradycardia). Examples include digoxin, clonidine, diltiazem, and verapamil.

• SildenafilMetoprolol may cause more of a drop in blood pressure if taken with PDE5 inhibitors.

• Alcohol: Some types of metoprolol (namely metoprolol succinate) are available in an extended-release formulation. In the presence of alcohol, this extended-release action is sped up, and the metoprolol is released into your system faster.

This list does not include all possible drug interactions with metoprolol and others may exist. Check with your pharmacist or healthcare provider for more information.

Certain groups of people should avoid using metoprolol or use it with caution (DailyMed, 2018):

• People with asthma: Metoprolol may trigger an asthma attack, and people with asthma or COPD should avoid using it. Make sure your healthcare provider is aware that you have asthma before starting metoprolol.

• People with Metoprolol can block the signs of low blood sugar, like increased heart rate, sweating, and tremors.

• People with a slow heart rate (bradycardia) or low blood pressure (hypotension): Metoprolol lowers blood pressure and heart rate.

• Pregnant women: The U.S. Food and Drug Administration (FDA) has deemed metoprolol as pregnancy category C; this means that there is not enough information to determine the risk to the pregnancy (FDA, 2006). Women and their healthcare providers should weigh the benefits of taking metoprolol against the risk to the fetus.

• Nursing mothers: Metoprolol does get into the breastmilk, in small quantities, and no adverse effects have been reported. Women and their healthcare providers should weigh the risks and benefits of the medication (FDA, 2006).

• People with liver disease: Since metoprolol is broken down by the liver, people with liver disease may have higher than expected levels of metoprolol in their system. They may need a lower dose of metoprolol (DailyMed, 2018).

This list does not include all possible at risk groups and others may exist. Check with your pharmacist or healthcare provider for more information.

There are two different types of metoprolol: metoprolol tartrate and metoprolol succinate. Metoprolol tartrate (brand name Lopressor) is used in immediate-release tablets and comes in 25 mg, 37.5 mg, 50 mg, 75 mg, and 100 mg pills. Metoprolol succinate (brand name Toprol XL) is used in the extended-release capsules and tablets and comes in 25 mg, 50 mg, 100 mg, and 200 mg pills. The specific dose recommended by your healthcare provider will vary depending on the condition being treated, as well as your other medical issues.

Both forms of metoprolol are available as generic medications. Metoprolol tartrate ranges from $4 to $9 for a 30-day supply, depending on the dose. Metoprolol succinate varies from $6 to $18 for a 30-day supply, again depending on the dose.

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Current version

August 13, 2020

Written by

Chimene Richa, MD

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.