How does this medication work? What will it do for me?

Metoprolol belongs to the class of medications called beta-blockers. Metoprolol is used to treat high blood pressure and prevent the symptoms of certain types of angina (chest pain). It is also used to help reduce the risk of death right after a heart attack. It works by reducing the demands put on the heart.

Metoprolol is also taken by people who have had a heart attack to reduce the risk of having another one. Metoprolol is often used in combination with other high blood pressure medications such as diuretics (water pills) when the use of one medication by itself is not enough to control blood pressure.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than the ones listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each mL of aqueous injectable solution contains metoprolol 1 mg and sodium chloride 9 mg.

How should I use this medication?

The usual maintenance dose of metoprolol ranges from 100 mg daily to 200 mg daily, however the dose may be increased to 400 mg daily if necessary to obtain symptom control. Immediate-release tablets are taken in 2 divided doses while slow-release tablets are taken once a day.

The medication may be taken with or without food. Try to take the doses of metoprolol at the same time each day.

The doctor may increase the dose if the desired results have not been achieved within one week. Once the best dose has been found with the immediate-release tablets, the slow-release tablets may be substituted at an equal daily dose for convenience.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take metoprolol if you:

  • are allergic to metoprolol or any ingredients of the medication
  • are allergic to other beta blockers
  • are scheduled to have anesthesia with an agent that causes myocardial depression (e.g., ether)
  • have a condition known as right ventricular failure caused by excessive blood pressure in the lungs
  • have a condition known as "sick sinus syndrome"
  • have a slow heartbeat caused by heart rhythm problems
  • have asthma or other obstructive respiratory diseases (for the intravenous form of metoprolol only)
  • have cardiogenic shock
  • have overt heart failure
  • have serious heart block
  • have severe circulatory disorders
  • have had a heart attack accompanied by:
    • a heart rate less than 45 beats per minute
    • significant heart block
    • very low blood pressure
    • moderate to severe cardiac failure

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal pain or discomfort
  • changes in sexual desire or ability
  • constipation
  • diarrhea
  • dizziness or lightheadedness
  • drowsiness (slight)
  • dry mouth
  • headache
  • increased sensitivity to sunlight
  • increased sweating
  • tiredness or weakness
  • vivid dreams
  • weight gain

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • back or joint pain
  • breathing difficulty or wheezing
  • chest pain
  • cold hands and feet
  • confusion
  • hallucinations (hearing or seeing things that aren't there)
  • red, scaling, or crusted skin
  • signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
  • signs of heart problems (e.g., fast, irregular heartbeat or pulse, chest pain, difficulty breathing, tiredness with activity, swelling of feet, ankles, or lower legs)
  • signs of kidney problems (e.g., increased need to urinate, decreased urine production, skin itching, nausea, vomiting, rash)
  • signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
  • slow heartbeat (especially less than 40 beats per minute)
  • tingling sensation in the extremities

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • fingers or toes cold to touch, painful or discoloured
  • symptoms of a serious allergic reaction (such as swelling of the face or throat, hives, or difficulty breathing)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Breathing conditions: Patients with asthma and certain other breathing problems should, in general, not take a beta-blocker such as metoprolol. If you have these types of conditions and your doctor prescribed metoprolol for you, it may be at a lower dose, and your doctor will monitor you regularly while you are taking this medication.

Diabetes: The signs of low blood sugar may not be as noticeable when taking metoprolol. This medication may make it more difficult for people with diabetes to control their blood sugar. If you have diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor will monitor you while you are taking this medication and may need to adjust the doses of antidiabetes medications.

Dizziness or fainting: Dizziness or fainting are side effects of metoprolol and may occur after first starting this medication. Avoid driving and other potentially hazardous tasks until you have determined how this medication affects you.

Heart disease: Beta-blockers, such as metoprolol, can worsen existing heart failure. It is important to take metoprolol exactly as prescribed by your doctor to decrease the chance of this happening. If you have a history of heart disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Hyperthyroidism (high level of thyroid hormones): If you have hyperthyroidism, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Stopping the medication suddenly could worsen this condition.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Severe allergies: If you have allergies severe enough to cause anaphylaxis (a severe allergic reaction where swelling of the face, lips, and throat make it difficult to breathe), discuss with your doctor about what to do if you have an allergic reaction. Metoprolol may make it more difficult to treat severe allergic reactions with epinephrine.

Stopping the medication: People with heart disease who stop taking this medication abruptly may experience severe effects, such as chest pain, irregular heartbeat, or heart attack. If you have heart disease, do not stop taking this medication without checking with your doctor first. When this medication needs to be stopped, it should be done gradually under supervision of your doctor.

Surgery: If you are scheduled for surgery, inform all health care professionals involved in your care that you are taking metoprolol.

Pregnancy: The medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking metoprolol, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: Normal adult doses of metoprolol may cause a drop in blood pressure that is larger than anticipated. Lower doses may be necessary for seniors.

What other drugs could interact with this medication?

There may be an interaction between metoprolol and any of the following:

  • acetylcholine
  • alcohol
  • alpha-1 blockers (e.g., doxazosin, prazosin, tamsulosin)
  • amphetamines (e.g., dextroamphetamine)
  • anesthetic agents
  • angiotensin converting enzyme inhibitors (ACEIs; e.g., captopril, ramipril)
  • angiotensin II receptor blockers (ARBs; e.g., irbesartan, losartan)
  • antiarrhythmic medications (e.g., amiodorone, quinidine, propafenone)
  • antidiabetes medications (e.g., glyburide, metformin, insulin)
  • antifungals (e.g., terbinafine)
  • antihistamines (e.g., diphenhydramine)
  • antimalarials (e.g., hydroxychloroquine, quinine)
  • antipsychotics (e.g., chlorpromazine, thioridazine)
  • aripiprazole
  • barbiturates
  • beta-agonists (asthma medications; e.g., salbutamol, salmeterol, formoterol)
  • beta-blockers (e.g., atenolol, metoprolol, propranolol)
  • bupropion
  • calcium channel blockers (e.g., verapamil, diltiazem, nifedipine, amlodipine)
  • celecoxib
  • clonidine
  • darunavir
  • digoxin
  • diuretics (water pills; e.g., furosemide, hydrochlorothiazide)
  • donepezil
  • epinephrine
  • epoprostenol
  • ergot derivatives (e.g., bromocriptine, ergotamine, methylergonovine)
  • fentanyl
  • floctafenine
  • galantamine
  • ginger
  • ginseng
  • imatinib
  • insulin
  • isoniazid
  • lidocaine
  • methacholine
  • methyldopa
  • methylphenidate
  • midodrine
  • monoamine oxidase (MAO) inhibitors (e.g., tranylcypromine, phenelzine)
  • nonsteroidal anti-inflammatories (NSAIDs; e.g., ibuprofen, indomethacin, naproxen)
  • norepinephrine
  • peginterferon alfa-2b
  • pentoxifylline
  • phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil)
  • pilocarpine
  • quinidine
  • rifampin
  • ritonavir
  • rituximab
  • rivastigmine
  • selective serotonin reuptake inhibitors (e.g., fluoxetine, paroxetine, sertraline)
  • theophylline
  • ticlopidine
  • yohimbine

If you are taking any medications containing this drug, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription) and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or illegal drugs can affect the action of many medications, you should let your prescriber know if you use them.