• Metoprolol is a medication that may be used to treat or prevent various heart conditions.
• Metoprolol works by blocking the effects of epinephrine on beta-1 receptors within the heart tissue, causing the heart to pump more slowly and with less force. At high doses, metoprolol also blocks beta-2 receptors within the lungs and airways (which may affect breathing).
• Metoprolol is available as two different salts: metoprolol tartrate and metoprolol succinate. These two salts are not interchangeable because they have different dosages, durations of action, and indications for use.
• Metoprolol belongs to a class of drugs known as beta-blockers.

Metoprolol tartrate

• Lowers blood pressure and relieves symptoms of angina in people with heart disease or who have had a heart attack.
• Immediate-release metoprolol tartrate has been shown to reduce the risk of death or another heart attack when given immediately following a heart attack.
• May also be used to lower the risk of a heart attack in people with heart disease.
• An injectable form is available which may be given by healthcare providers for people with unstable angina or arrhythmia.
• May be used off-label for other conditions such as migraine prevention and to treat certain arrhythmias.
• Classified as a "selective" beta-blocker meaning it is less likely to affect breathing and insulin response than other nonselective beta-blockers.
• Generic forms are available.

Metoprolol succinate

• Lowers blood pressure and relieves symptoms of angina in people with heart disease.
• Slow-release forms may be beneficial in people with certain types of heart failure.
• Available as a slow-release tablet which is usually dosed once a day.
• Classified as a "selective" beta-blocker meaning it is less likely to affect breathing and insulin response than other nonselective beta-blockers.
• Generic forms are available.

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Heart rate slowing, depression, diarrhea, skin rash, and shortness of breath. Side effects are similar for both metoprolol tartrate and metoprolol succinate because they both contain the same active drug, metoprolol.
• Dry eyes, blurred vision, dizziness (particularly when rising from a sitting to a standing position), fatigue, nightmares, a slow heartbeat, and sweating are common
• Less common side effects include facial and limb swelling, headache, visual disturbances, and tingling of the hands or feet
• Avoid abrupt discontinuation. Stopping metoprolol (both tartrate and succinate) suddenly can exacerbate angina and may increase the risk of a heart attack. Reduce dosage gradually over a few weeks as instructed by your doctor
• May interfere slightly with laboratory cholesterol results
• 8% of the Caucasian population and approximately 2% of other populations have a reduced ability to metabolize metoprolol and their dosage of metoprolol may need reducing
• May not be suitable for some people including those with heart block greater than 1st degree, pheochromocytoma, poor circulation, sick sinus syndrome, a thyroid disorder, overt or decompensated heart failure, or who are under the age of 18
• Should be used with caution in people with pre-existing respiratory disease
• May decrease symptoms of low blood sugar (hypoglycemia) (such as a fast heart rate, palpitations, tremors, or feelings of anxiety) and increase the risk of insulin-induced hypoglycemia.
• May also mask signs of high thyroid levels (hyperthyroidism) (such as a fast heart rate). May precipitate a thyroid storm if abruptly stopped
• May interact with some other medications including antidepressants, antipsychotics, ergot alkaloids, or some other blood pressure medications.

Metoprolol tartrate:

• Only available as an immediate-release tablet which means it must be taken several times per day.

Metoprolol succinate:

• Should not be used to prevent heart attacks.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

• Take metoprolol at the same time each day.
• Report any shortness of breath or facial swelling immediately to your doctor.
• Also, talk to your doctor if you develop a very slow heartbeat or cold feeling in your hands or feet.
• If you are diabetic, talk to your doctor about the possibility that metoprolol may reduce your symptoms of hypoglycemia.
• Talk to your doctor if you are having any side effects that are interfering with your quality of life. Do not stop taking metoprolol suddenly.
• Do not substitute metoprolol tartrate with metoprolol succinate and vice versa.
• Always check that your prescription is correct. There have been several dosing errors involving metoprolol tablets.
• Your doctor will need to regularly monitor your blood pressure and possibly other markers. Keep your appointments.
• Metoprolol may impair your thinking or reaction time and affect your ability to drive. Drinking alcohol may enhance these effects. Do not drive if you think your driving ability is being compromised by metoprolol.

Metoprolol tartrate

• Food can affect absorption. Take tablets with or immediately after food.

Metoprolol succinate

• Can be taken once daily.
• Metoprolol succinate tablets can be taken with or without food.
• Extended-release tablets may be scored or divided; however, they should not be crushed or chewed.

• With oral metoprolol tartrate, significant effects on the heart rate are seen within an hour, and effects last for six to 12 hours depending on the dose. With injectable metoprolol tartrate, significant effects are seen within 20 minutes, and a single injection lasts for approximately 5 to 8 hours, depending on the dose. The duration of effect is dependent on the dose (meaning that larger dosages of metoprolol have a longer duration of action).
• With oral metoprolol succinate extended-release (ER) tablets, peak concentrations are reached in about seven hours following a single dose. With regular dosing; however, concentrations of metoprolol remain steady and do not fluctuate much. ER tablets are usually dosed once daily. The blood pressure-lowering effects of ER tablets persist for about 24 hours.

Medicines that interact with metoprolol may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with metoprolol. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with metoprolol include:

• antidepressants, such as fluoxetine, paroxetine, St John’s Wort, and monoamine oxidase inhibitors
• antifungals, such as terbinafine
• antihistamines, such as diphenhydramine
• bupropion, which may be used for the treatment of depression and as a stop-smoking aid
• antimalaria agents, such as hydroxychloroquine
• fingolimod, which may be used for the treatment of multiple sclerosis
• HIV medications such as ritonavir
• indigestion and heartburn medications, such as cimetidine and ranitidine
• some medications used to treat mental illness, such as thioridazine
• some heart medications, such as amiodarone, clonidine, digoxin, diltiazem, propafenone, quinidine, and verapamil
• other medications including celecoxib, clonidine, hydralazine, and rifampicin
• NSAIDs, such as diclofenac, ibuprofen, and indomethacin, may decrease the blood pressure-lowering capabilities of metoprolol.

People taking oral medications for diabetes may need to talk to their doctor about adjusting the dose of their medicine.

Note that this list is not all-inclusive and includes only common medications that may interact with metoprolol. You should refer to the prescribing information for metoprolol for a complete list of interactions.