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

Side Effects of Propranolol

Propranolol causes a wide range of adverse effects across multiple organ systems, with the most clinically significant being cardiovascular (bradycardia, hypotension, heart failure), respiratory (bronchospasm), and central nervous system effects (sleep disturbances, fatigue, depression). 1

Cardiovascular Side Effects

The cardiac effects are among the most important to monitor:

• Bradycardia and hypotension occur commonly due to beta-receptor blockade, with rates varying widely across studies 2, 1
• Congestive heart failure can be precipitated or worsened, particularly in patients with pre-existing ventricular dysfunction, as beta-blockade inhibits compensatory sympathetic stimulation 1
• Intensification of AV block is a recognized complication that may require treatment modification 1
• Peripheral vascular effects including cold extremities and arterial insufficiency (Raynaud-type) occur due to peripheral vasoconstriction 2, 3, 1
• In pediatric patients treated for infantile hemangiomas, bradycardia and hypotension tend to be mild and asymptomatic when no cardiac comorbidities exist, with rates as low as 0.1% for symptomatic bradycardia 2

Respiratory Side Effects

Bronchospasm is a serious and potentially life-threatening adverse effect:

• Propranolol is contraindicated in patients with reactive airway disease including asthma and should be used with extreme caution in chronic obstructive pulmonary disease 2, 1
• Bronchial irritation, hyperreactivity, and cold-induced wheezing occur in 3-13% of patients 2
• In patients with chronic obstructive lung disease, propranolol causes significant reductions in FEV1 and blocks isoprenaline-mediated bronchodilation 4, 5, 6
• Respiratory adverse effects may require temporary discontinuation or dose reduction 2

Central Nervous System and Psychiatric Effects

Sleep disturbances are among the most common CNS side effects:

• Sleep disorders, nightmares, night terrors, and nocturnal agitation occur in 2-18.5% of patients 2, 7
• These effects result from propranolol's lipophilic properties allowing blood-brain barrier penetration 2, 7
• Management strategies include dose reduction, earlier-evening dosing, or switching to a less lipophilic beta-blocker 7

Other CNS effects include:

• Fatigue and lethargy appear dose-related with immediate-release formulations 8, 1
• Mental depression manifested by insomnia, lassitude, and weakness 1
• Cognitive effects including lightheadedness, visual disturbances, hallucinations, vivid dreams, and an acute reversible syndrome with disorientation, short-term memory loss, and emotional lability 1
• In pediatric patients, lethargy may indicate hypoglycemia and requires immediate evaluation 8

Gastrointestinal Side Effects

• Common GI symptoms include nausea, vomiting, epigastric distress, abdominal cramping, diarrhea, and constipation 2, 1
• Serious complications such as mesenteric arterial thrombosis and ischemic colitis can occur rarely 1

Metabolic and Endocrine Effects

Hypoglycemia is a critical concern, particularly in vulnerable populations:

• Beta-blockade masks premonitory signs of hypoglycemia (tachycardia, tremor) making detection difficult, especially in insulin-dependent diabetics 1
• Propranolol-associated hypoglycemia occurs particularly in infants, children, patients fasting for surgery, after prolonged exercise, and in renal insufficiency 2, 1
• In pediatric patients with infantile hemangiomas, clinicians must evaluate for hypoglycemia as a cause of lethargy 2, 8
• Hyperglycemia is also listed as a potential adverse effect 2

Dermatologic and Allergic Reactions

Serious skin reactions, though rare, can be life-threatening:

• Severe cutaneous reactions include Stevens-Johnson Syndrome, toxic epidermal necrolysis, exfoliative dermatitis, and erythema multiforme 1
• Hypersensitivity reactions including anaphylactic/anaphylactoid reactions have been reported 1
• Common skin effects include cold extremities (due to peripheral vasoconstriction), urticaria, erythematous rash, and alopecia 2, 3, 1
• Autoimmune manifestations such as systemic lupus erythematosus-like reactions and psoriasiform rashes can occur 1

Hematologic Effects

• Blood dyscrasias including agranulocytosis, thrombocytopenic purpura, and nonthrombocytopenic purpura are rare but serious complications 1

Genitourinary Effects

• Male sexual dysfunction including impotence and Peyronie's disease have been reported 1

Special Populations and Clinical Contexts

Pediatric patients (infantile hemangiomas):

• The American Academy of Pediatrics recommends evaluating and educating caregivers about sleep disturbances, bronchial irritation, and clinically symptomatic bradycardia and hypotension 2
• Treatment modifications (dose reduction, timing changes, or discontinuation) occurred in response to adverse effects in multiple case series 2

Post-myocardial infarction patients:

• In the Beta-Blocker Heart Attack Trial, bronchospasm, cold hands and feet, and fatigue occurred more frequently in the propranolol group, though serious side effects were uncommon overall 9, 10
• Hypotension, gastrointestinal problems, and tiredness were also more common with propranolol 10

Critical Warnings

Abrupt discontinuation risks:

• Sudden withdrawal can precipitate exacerbation of angina, myocardial infarction, or thyroid storm in hyperthyroid patients 1
• Propranolol should be tapered gradually over at least several weeks 1

Surgical considerations:

• Beta-blockade impairs the heart's ability to respond to reflex adrenergic stimuli, augmenting risks of general anesthesia 1

Thyroid disease:

• Beta-blockade masks clinical signs of hyperthyroidism and can alter thyroid function tests 1