Metoprolol

What Is Metoprolol and What Is It Used For?

Metoprolol belongs to a group of medications known as beta-adrenergic receptor blockers, commonly called beta blockers. It works by selectively blocking beta-1 adrenergic receptors, which are primarily found in heart tissue. By blocking these receptors, metoprolol reduces the heart's response to stress hormones such as adrenaline (epinephrine) and noradrenaline (norepinephrine). This results in a slower heart rate, reduced force of heart contractions, and lower blood pressure, particularly during physical or emotional stress.

Metoprolol is classified as a beta-1 selective (or "cardioselective") beta blocker. At therapeutic doses, it preferentially blocks beta-1 receptors in the heart with relatively less effect on beta-2 receptors in the lungs and blood vessels. This selectivity makes it somewhat better tolerated than non-selective beta blockers in patients with mild asthma or peripheral vascular disease, although caution is still required in these populations. At higher doses, the selectivity diminishes and some beta-2 blockade may occur.

Metoprolol is one of the most widely prescribed cardiovascular medications in the world and has been included on the WHO Model List of Essential Medicines since its introduction. It has an extensive evidence base spanning decades of clinical research, including landmark heart failure trials (MERIT-HF) and post-myocardial infarction studies that have shaped international treatment guidelines.

Approved Indications

Metoprolol is approved and used for the treatment of:

• Hypertension (high blood pressure) — Metoprolol lowers blood pressure by reducing cardiac output and heart rate. It is used alone or in combination with other antihypertensive agents such as ACE inhibitors, angiotensin receptor blockers, or diuretics. The 2023 ESH guidelines recognize beta blockers as appropriate initial therapy particularly when there are compelling indications such as heart failure or post-MI.
• Angina pectoris (chest pain) — By reducing heart rate and myocardial oxygen demand, metoprolol prevents episodes of exertional chest pain caused by insufficient blood flow to the heart muscle. It is a first-line treatment according to ESC guidelines for chronic coronary syndromes.
• Cardiac arrhythmias — Metoprolol is effective in controlling ventricular rate in supraventricular tachycardias, including atrial fibrillation and atrial flutter. It also helps manage ventricular arrhythmias associated with excessive sympathetic drive.
• Functional heart palpitations — Used to reduce awareness of heartbeat (palpitations) caused by non-organic cardiac conditions, such as anxiety-related tachycardia.
• Stable heart failure — Metoprolol succinate (extended-release) is one of only three beta blockers proven to reduce mortality in chronic heart failure with reduced ejection fraction (HFrEF), alongside bisoprolol and carvedilol. Treatment is initiated at low doses and gradually uptitrated. The MERIT-HF trial demonstrated a 34% reduction in all-cause mortality.
• Secondary prevention after myocardial infarction — Metoprolol reduces the risk of recurrent heart attacks and sudden cardiac death when started after an acute myocardial infarction. Beta blocker therapy post-MI is a Class I recommendation in ESC and AHA/ACC guidelines.
• Migraine prophylaxis — Metoprolol is effective in reducing the frequency and severity of migraine attacks. It is recommended as a first-line preventive treatment in international migraine guidelines (EHF, AAN) for patients with frequent migraines.

Pediatric Use

Metoprolol is approved for the treatment of hypertension in children and adolescents aged 6 to 18 years. The dose is calculated based on body weight, starting at 0.5 mg/kg of metoprolol tartrate equivalent once daily, with the option to increase up to 2 mg/kg daily depending on the blood pressure response. Metoprolol is not recommended for children under 6 years of age due to limited safety and efficacy data in this population.

What Should You Know Before Taking Metoprolol?

Before starting metoprolol, your doctor will evaluate your medical history, current medications, and any existing conditions that could affect how safely you can take this medication. Open and honest communication with your healthcare provider is essential to minimize risks and optimize treatment outcomes.

Contraindications

You should not take metoprolol if you have any of the following conditions:

• Known allergy to metoprolol, other beta blockers, or any of the inactive ingredients in the formulation
• Decompensated (unstable) heart failure requiring intravenous inotropic support
• Heart failure with systolic blood pressure below 100 mmHg
• Severe bradycardia — resting heart rate below 45 beats per minute
• Hypotension — clinically significant low blood pressure
• Cardiogenic shock — a life-threatening condition where the heart cannot pump enough blood
• Second- or third-degree atrioventricular (AV) block — a serious conduction abnormality in the heart (unless a pacemaker is present)
• Sick sinus syndrome — dysfunction of the heart's natural pacemaker (unless a permanent pacemaker is implanted)
• Severe peripheral arterial disease — conditions with critically reduced blood flow to the extremities, such as critical limb ischemia

Warnings and Precautions

Talk to your doctor before taking metoprolol if any of the following apply to you:

• Asthma or chronic obstructive pulmonary disease (COPD) — Although metoprolol is beta-1 selective, it can still cause bronchospasm in susceptible individuals. Your doctor may consider alternative treatments or use the lowest effective dose with careful monitoring of respiratory function.
• Diabetes mellitus — Metoprolol can mask the typical symptoms of low blood sugar (hypoglycemia), particularly rapid heartbeat and tremor. Sweating may still occur. Patients with diabetes should monitor blood glucose more frequently, especially during dose adjustments.
• Peripheral circulatory disorders — Metoprolol may worsen symptoms of poor circulation, leading to cold, numb, or tingling fingers and toes (Raynaud's phenomenon).
• Prinzmetal's angina (vasospastic angina) — Beta blockers may paradoxically worsen coronary vasospasm in this condition.
• First-degree AV block — Metoprolol may prolong conduction time and worsen the block.
• Pheochromocytoma — If you have this rare adrenal tumor, metoprolol should only be used after adequate alpha-blocker therapy has been established, to prevent a hypertensive crisis.
• Severe hepatic (liver) impairment — Metoprolol is extensively metabolized by the liver. Dose adjustments may be necessary in patients with severe liver disease.
• Severe renal (kidney) impairment — Although metoprolol is primarily hepatically cleared, caution is warranted in severe kidney disease.
• Planned surgery or anesthesia — Inform your anesthetist that you are taking metoprolol, as it can interact with inhalation anesthetics and enhance cardiac depressant effects.
• History of severe allergic reactions — Beta blockers may enhance sensitivity to allergens and increase the severity of anaphylactic reactions. They may also reduce the effectiveness of epinephrine (adrenaline) used to treat anaphylaxis.
• Metabolic acidosis — Metoprolol should be used with caution, as acidosis can enhance the cardiac depressant effects of beta blockers.

Pregnancy and Breastfeeding

Beta blockers, including metoprolol, can cross the placenta and potentially reduce heart rate in the fetus and newborn. Metoprolol has been associated with intrauterine growth restriction in some studies, although the evidence is mixed. Metoprolol is generally not recommended during pregnancy unless the potential benefit to the mother clearly outweighs the risk to the fetus.

If antihypertensive treatment is required during pregnancy, your doctor may consider medications with a more established safety profile, such as labetalol, methyldopa, or nifedipine. However, if you become pregnant while taking metoprolol, do not stop the medication on your own — consult your doctor promptly to discuss the best course of action.

Metoprolol is excreted in breast milk, although the amount transferred to the nursing infant is generally considered small. Breastfeeding is generally not recommended during metoprolol therapy unless deemed necessary by your physician. If breastfeeding is continued, the infant should be monitored for signs of bradycardia and hypotension.

Driving and Operating Machinery

Metoprolol can cause dizziness, fatigue, and visual disturbances, particularly at the start of treatment or when the dose is changed. You should assess how the medication affects you before driving or operating machinery. Alcohol may enhance these effects and should be consumed with caution.

How Does Metoprolol Interact with Other Drugs?

Metoprolol is metabolized primarily by the cytochrome P450 enzyme CYP2D6 in the liver. Drugs that inhibit CYP2D6 can significantly increase metoprolol blood levels, potentially leading to excessive beta-blockade. Additionally, the pharmacological effects of metoprolol can be enhanced or opposed by other cardiovascular and non-cardiovascular drugs. Understanding these interactions is crucial for safe and effective treatment.

Approximately 7–10% of Caucasians and 1–2% of most other populations are CYP2D6 poor metabolizers, meaning they have genetically reduced enzyme activity. These individuals will have significantly higher metoprolol levels and may require lower doses. Genetic testing for CYP2D6 is available but not routinely performed.

Major Interactions

Moderate Interactions

What Is the Correct Dosage of Metoprolol?

Metoprolol dosage varies widely depending on the medical condition being treated, the specific formulation used (succinate vs. tartrate), the patient's age, kidney/liver function, and individual response. The extended-release formulation (metoprolol succinate) is designed to be taken once daily, while the immediate-release form (metoprolol tartrate) is typically divided into two or more daily doses. The doses are not directly interchangeable: 47.5 mg metoprolol succinate = 50 mg metoprolol tartrate.

Extended-release tablets should be swallowed whole with a glass of water, preferably in the morning. They may be halved to make swallowing easier, but should never be crushed or chewed, as this would destroy the extended-release mechanism and release the full dose at once.

Adults

Children (6–18 years)

Metoprolol is used to treat hypertension in children and adolescents aged 6 to 18 years. Dosing is weight-based:

• Starting dose: 0.5 mg/kg metoprolol tartrate equivalent once daily (rounded to the nearest available tablet strength)
• Dose adjustment: If blood pressure is not adequately controlled, the dose can be increased to 1.0 mg/kg once daily
• Maximum dose: 2.0 mg/kg once daily, not exceeding 200 mg/day

For example, a child weighing 25 kg would typically start with half a 25 mg tablet (12.5 mg) once daily, with the option to increase to a 50 mg tablet if needed. Doses above 200 mg daily have not been studied in the pediatric population.

Elderly and Hepatic Impairment

No specific dose adjustment is routinely required for elderly patients solely based on age. However, elderly patients are more susceptible to bradycardia, hypotension, and dizziness, so treatment should typically begin at the lower end of the dosing range with careful monitoring. In patients with severe liver impairment, metoprolol clearance is significantly reduced, and the dose may need to be lowered. Your doctor will determine the appropriate adjustment based on clinical response and liver function tests.

Missed Dose

If you forget to take a dose of metoprolol, take it as soon as you remember. If it is close to the time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for a forgotten one. If you frequently forget doses, consider setting a daily alarm or using a pill organizer to help maintain a consistent dosing routine.

Overdose

Metoprolol overdose can be serious and potentially life-threatening. Symptoms may include severe bradycardia (very slow heart rate), hypotension (dangerously low blood pressure), heart failure, cardiogenic shock, bronchospasm, impaired consciousness, and in severe cases, cardiac arrest. If you suspect an overdose, seek emergency medical attention immediately by calling your local emergency number or contacting a poison control center. Treatment is supportive and may include atropine for bradycardia, IV fluids, vasopressors, glucagon, and in severe cases, cardiac pacing.

What Are the Side Effects of Metoprolol?

Like all medications, metoprolol can cause side effects, although not everyone experiences them. The majority of side effects are related to the drug's primary pharmacological action — blocking beta-adrenergic receptors — and are dose-dependent. Many patients find that side effects are most prominent during the first few weeks of treatment and tend to diminish as the body adjusts. If you experience persistent or troublesome side effects, speak to your doctor before making any changes to your treatment.

The side effects listed below are categorized by frequency according to the standard system used in medical literature:

It is important to report any suspected side effects to your healthcare provider. Continued monitoring helps maintain the benefit-risk balance of the medication and contributes to the ongoing safety assessment of metoprolol in the wider population.

How Should You Store Metoprolol?

Proper storage of metoprolol is important to ensure the medication remains effective and safe throughout its shelf life. Follow these storage guidelines:

• Temperature: Store at or below 30°C (86°F). Do not refrigerate or freeze.
• Moisture protection: Keep the tablets in their original blister packaging or container to protect from humidity. Do not store in the bathroom.
• Light protection: Avoid prolonged exposure to direct sunlight.
• Child safety: Keep all medications out of the sight and reach of children. Use child-resistant containers where available.
• Expiry date: Do not use metoprolol after the expiry date printed on the packaging (EXP). The expiry date refers to the last day of that month.

Do not dispose of unused medications via household waste or wastewater drainage. Return unused or expired metoprolol to your local pharmacy for safe disposal. This helps protect the environment and prevents accidental ingestion.

What Does Metoprolol Contain?

Metoprolol is available in two salt forms, each with distinct pharmacokinetic properties:

• Metoprolol succinate — Used in extended-release (controlled-release) formulations. The succinate salt allows for gradual drug release, providing consistent plasma levels over 24 hours with once-daily dosing. Strengths: 23.75 mg, 47.5 mg, 95 mg, and 190 mg metoprolol succinate (equivalent to 25 mg, 50 mg, 100 mg, and 200 mg metoprolol tartrate, respectively).
• Metoprolol tartrate — Used in immediate-release formulations. The tartrate salt is rapidly absorbed and typically requires twice-daily dosing. Also available as an injection solution (1 mg/mL) for intravenous use in acute clinical settings.

Common excipients (inactive ingredients) in extended-release tablets include: colloidal silicon dioxide, microcrystalline cellulose, hypromellose, sodium lauryl sulfate, polysorbate 80, glycerol, hydroxypropyl cellulose, ethylcellulose, sodium stearyl fumarate (tablet core), and hypromellose, titanium dioxide (E171), talc, and propylene glycol (film coating).

Metoprolol extended-release tablets contain less than 1 mmol (23 mg) sodium per tablet and are essentially sodium-free. Patients on sodium-restricted diets do not need to account for sodium content from this medication.

Metoprolol is available in tablet form as white to off-white, oval, biconvex film-coated tablets with a score line. The 25 mg tablet may be split into two equal halves. The 50 mg, 100 mg, and 200 mg tablets may be halved to make swallowing easier, but this does not produce equal doses.