What are the side effects of metoprolol (beta-blocker)?

Side Effects of Metoprolol

Metoprolol commonly causes tiredness, dizziness, bradycardia, and hypotension, with most adverse effects being mild and transient, though serious cardiovascular complications including heart failure exacerbation and bronchospasm can occur in susceptible patients. 1

Common Side Effects

Central Nervous System Effects

• Tiredness and dizziness occur in approximately 10% of patients, representing the most frequent adverse reactions 1
• Depression affects about 5% of patients 1
• Mental confusion, short-term memory loss, headache, nightmares, and insomnia have been reported 1
• Sleep disturbances including nightmares and night terrors can occur 2

Cardiovascular Effects

• Bradycardia (heart rate <40 beats/min) occurs in approximately 16% of patients treated for myocardial infarction 1
• Hypotension (systolic BP <90 mmHg) develops in about 27% of MI patients 1
• Shortness of breath and bradycardia occur in approximately 3% of hypertension/angina patients 1
• Cold extremities, arterial insufficiency (usually Raynaud type), palpitations, and peripheral edema affect about 1% of patients 1
• Heart failure can be precipitated or worsened, as beta-blockers cause myocardial depression 1

Respiratory Effects

• Wheezing (bronchospasm) and dyspnea occur in approximately 1% of patients 1
• Patients with bronchospastic disease should generally not receive beta-blockers, though metoprolol's relative beta-1 selectivity may allow cautious use 1
• Bronchodilators including beta-2 agonists should be readily available 1

Gastrointestinal Effects

• Diarrhea occurs in about 5% of patients 1
• Nausea, dry mouth, gastric pain, constipation, flatulence, and heartburn affect about 1% of patients 1
• Very rare reports of hepatitis, jaundice, and non-specific hepatic dysfunction have been documented 1

Other Common Effects

• Pruritus or rash occur in about 5% of patients 1
• Fatigue is frequently reported 3, 4

Serious Adverse Effects and Warnings

Cardiac Complications

• Beta-blockers can cause depression of myocardial contractility and may precipitate heart failure and cardiogenic shock 1
• Second- or third-degree heart block occurs in 4.7% of patients 1
• First-degree heart block (P-R ≥0.26 sec) occurs in 5.3% of patients 1
• Severe bradycardia including sinus pause, heart block, and cardiac arrest have occurred; patients with first-degree AV block, sinus node dysfunction, or conduction disorders are at increased risk 1
• Gangrene in patients with pre-existing severe peripheral circulatory disorders has been reported very rarely 1

Abrupt Discontinuation Risks

• Do not abruptly discontinue metoprolol in patients with coronary artery disease 1
• Severe exacerbation of angina, myocardial infarction, and ventricular arrhythmias have been reported following abrupt discontinuation 1
• When discontinuing chronically administered metoprolol, dosage should be gradually reduced over 1-2 weeks with careful monitoring 1

Metabolic Effects

• Beta-blockers may mask tachycardia occurring with hypoglycemia, though other manifestations like dizziness and sweating may not be significantly affected 1
• This is particularly important in diabetic patients 2, 1
• First- and second-generation beta-blockers are associated with increased incidence of new-onset diabetes 2
• Unfavorable changes in blood lipids have been reported 2

Bronchospastic Disease

• Patients with bronchospastic disease should generally not receive beta-blockers 1
• Due to relative beta-1 selectivity, metoprolol may be used cautiously in patients who don't respond to other treatments 1
• Use the lowest possible dose and consider three-times-daily dosing instead of twice-daily to avoid higher plasma levels 1
• Beta-blockers are typically avoided in patients with severe pulmonary disease, particularly those with bronchospasm 2

Special Populations and Considerations

Pregnancy

• Metoprolol is considered safe in pregnancy 2

Elderly Patients

• Topical and systemic co-administration of beta-blockers is frequently observed in elderly patients and may result in additive effects including risk of bradycardia 2
• Lowering heart rate too much in the elderly with beta-blocker treatment may cause serious adverse events 2

Drug Interactions

• Concurrent medications that lower blood pressure can increase risk of hypotension 5
• The risk of hypotension increases with polypharmacy, especially in elderly patients 5

Clinical Monitoring Recommendations

• Monitor heart rate and rhythm in patients receiving metoprolol 1
• If severe bradycardia develops, reduce or stop metoprolol 1
• Monitor for signs of heart failure symptoms, fluid retention, hypotension, and bradycardia during titration 2
• If worsening symptoms occur, first increase diuretics or ACE-inhibitor dose; temporarily reduce beta-blocker dose if necessary 2

Rare Adverse Effects

• Peyronie's disease reported in fewer than 1 in 100,000 patients 1
• Musculoskeletal pain, blurred vision, and tinnitus 1
• Rare reports of reversible alopecia, agranulocytosis, and dry eyes 1
• Very rare reports of weight gain, arthritis, and retroperitoneal fibrosis 1
• Photosensitivity and worsening of psoriasis reported very rarely 1