What are the side effects of propranolol?

Side Effects of Propranolol

Propranolol has multiple potential side effects including cardiovascular effects (bradycardia, hypotension), respiratory effects (bronchospasm), central nervous system effects (sleep disturbances, depression), gastrointestinal effects, and metabolic effects (hypoglycemia), with the most clinically significant being hypoglycemia, bronchospasm, and cardiovascular depression. 1, 2

Cardiovascular Side Effects

• Bradycardia (heart rate <50 beats/min) - occurs in approximately 20% of overdose cases 3
• Hypotension (systolic blood pressure <90 mmHg) - occurs in approximately 42% of overdose cases 3
• Intensification of AV block 2
• Congestive heart failure - can precipitate heart failure in susceptible patients 2
• Raynaud's phenomenon (arterial insufficiency) 2

Central Nervous System Effects

• Sleep disturbances - occurring in 2% to 18.5% of patients 1
• Mental depression manifested by insomnia, lassitude, weakness, fatigue 2
• Lightheadedness 2
• Visual disturbances and hallucinations 2
• Vivid dreams - appears to be dose-related 2
• Acute reversible syndrome with disorientation, short-term memory loss, emotional lability 2
• Seizures - can occur in overdose (8% of cases) 3
• Coma - can occur in overdose (14% of cases) 3

Respiratory Effects

• Bronchospasm - particularly in patients with underlying respiratory disease 1, 2
• Respiratory disorders reported in 3.4% of patients 1
• Wheezing or bronchiolitis reported in 12.9% of patients 1
• Labored breathing in 0.9% of patients 1

Gastrointestinal Effects

• Nausea and vomiting 2
• Epigastric distress and abdominal cramping 2
• Diarrhea - can be severe enough to warrant discontinuation 2, 4
• Constipation 2

Metabolic Effects

• Hypoglycemia - particularly concerning in:
  • Infants and children (diabetic or not) 2
  • Patients fasting (e.g., before surgery) 2
  • After prolonged physical exertion 2
  • Patients with renal insufficiency 2
• Beta-blockade may mask early warning signs of hypoglycemia (sweating, tachycardia) 1, 5, 2

Other Side Effects

• Allergic reactions including anaphylaxis 2
• Skin reactions (Stevens-Johnson Syndrome, toxic epidermal necrolysis, exfoliative dermatitis) 2
• Male impotence 2
• Cold extremities 1

Severe Toxicity in Overdose

• Severe toxicity threshold appears to be around 2,000 mg in isolated propranolol overdose 3
• Cardiac arrest can occur at higher doses (reported range 2,400-16,000 mg) 3
• Sodium channel blockade effects on ECG in 8% of overdose cases 3

Management of Side Effects

• For sleep disturbances: Consider dose reduction, earlier-evening dosing, or early discontinuation 1
• For respiratory side effects: Consider temporary discontinuation or decreased dosage 1
• For hypoglycemia risk: Administer propranolol with or after feeding 1
• Hold doses during times of diminished oral intake or vomiting 1

Important Precautions

• Never abruptly discontinue propranolol - can exacerbate angina or precipitate myocardial infarction 2
• Gradual tapering over several weeks is recommended when discontinuing 2
• Use with extreme caution in patients with:
  • Congestive heart failure 2
  • Bronchospastic lung disease 2
  • Diabetes (may mask hypoglycemia symptoms) 2
  • Thyrotoxicosis (may mask symptoms) 2
  • Wolff-Parkinson-White syndrome 2

Monitoring Recommendations

• Regular assessment of heart rate and blood pressure
• Monitoring for signs of bronchospasm in susceptible patients
• Education of caregivers about potential adverse effects 1
• Close monitoring for hypoglycemia, particularly in high-risk groups 1, 2

Propranolol is generally well-tolerated, with severe side effects necessitating withdrawal occurring in less than 10% of patients and dose-limiting side effects in less than 15% 6. However, vigilant monitoring and patient education are essential to minimize risks and optimize outcomes.