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

Metoprolol Side Effects

The most common side effects of metoprolol include fatigue, dizziness, bradycardia (slow heart rate), hypotension, shortness of breath, cold extremities, and gastrointestinal disturbances such as nausea and diarrhea. 1 These side effects are generally mild and transient but can significantly impact quality of life in some patients.

Central Nervous System Effects

• Fatigue and dizziness: Occur in approximately 10% of patients 1
• Depression: Reported in about 5% of patients 1
• Mental confusion and short-term memory loss: Less common but reported 1
• Headache, nightmares, and insomnia: Also reported 1
• Visual hallucinations: Though rare, case reports describe patients experiencing visual hallucinations at night that resolved upon discontinuation of metoprolol 2

Cardiovascular Effects

• Bradycardia: Occurs in approximately 3% of patients during regular use 1, but can be more common (15.9%) in post-myocardial infarction settings 1
• Cold extremities and Raynaud's phenomenon: Reported in about 1% of patients 1
• Hypotension: Can occur, especially when initiating therapy 1
• Heart failure exacerbation: Reported in patients with underlying cardiac dysfunction 1
• Peripheral edema: Occurs in approximately 1% of patients 1

Respiratory Effects

• Wheezing and bronchospasm: Occurs in about 1% of patients, particularly those with underlying respiratory conditions 1
• Dyspnea: Shortness of breath reported in approximately 3% of patients 1
• Rhinitis: Also reported 1

Gastrointestinal Effects

• Diarrhea: Occurs in about 5% of patients 1
• Nausea, dry mouth, gastric pain, constipation: Each reported in approximately 1% of patients 1
• Vomiting: Common occurrence 1

Metabolic and Endocrine Effects

• Masking of hypoglycemia symptoms: Beta-blockers can mask early warning signs of hypoglycemia such as sweating and tachycardia 3
• Increased blood triglycerides and decreased HDL: Reported in post-marketing surveillance 1
• Unstable diabetes: Has been reported, though causality not firmly established 1

Dermatologic Effects

• Pruritus or rash: Occurs in about 5% of patients 1
• Photosensitivity and worsening of psoriasis: Very rare 1
• Reversible alopecia: Rare 1

Special Considerations and Risk Management

Gradual Discontinuation

• Abrupt discontinuation can be dangerous: May lead to rebound hypertension, angina exacerbation, and in rare cases, myocardial infarction 4
• Tapering recommendation: Gradually reduce dose over 1-2 weeks when discontinuing therapy

Contraindications and Cautions

• Asthma and COPD: Use with extreme caution due to risk of bronchospasm 4
• Diabetes: May mask symptoms of hypoglycemia 3
• Heart block or bradycardia: May worsen these conditions 1
• Peripheral vascular disease: May exacerbate symptoms 1
• Depression: May worsen depressive symptoms 1

Monitoring Recommendations

• Monitor heart rate and blood pressure regularly
• Watch for signs of heart failure (weight gain, edema, increased dyspnea)
• In diabetic patients, more frequent blood glucose monitoring may be needed
• Be alert for mood changes, especially depression

Patient Education Points

• Take medication as prescribed, even when feeling well
• Report significant side effects, especially dizziness, persistent fatigue, or mood changes
• Do not stop taking metoprolol suddenly without medical supervision
• Be aware of potential for cold extremities, especially in cold weather
• Diabetic patients should monitor blood glucose more frequently and be aware that warning signs of hypoglycemia may be masked

While metoprolol is generally well-tolerated compared to non-selective beta-blockers, awareness of these potential side effects is important for optimal patient management and medication adherence.