← All causality assessments
Expected pharmacological effect
Causality assessment · Expected pharmacological effect
Propranolol (beta-blockers) and Bradycardia / bronchospasm: is the FAERS signal real?
A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.
Propranolol (beta-blockers) ↔ Bradycardia / bronchospasm
n=1,448 co-reports · PRR 8.2 · ROR 8.3
Propranolol blocks cardiac beta-1 receptors and bronchial beta-2 receptors, so slowing the heart rate and provoking bronchospasm are direct, predictable consequences of its pharmacology rather than idiosyncratic reactions. Bradycardia is dose-related and amplified by other rate-slowing drugs; bronchospasm matters most in asthma and COPD. The 1,448 co-reports (PRR 8.2) reflect both the drug's genuine effects and how long and widely non-selective beta-blockers have been prescribed.
Regulatory basis: propranolol prescribing information (bradycardia, bronchospasm; contraindication in asthma).
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Heart-rate slowing and wheeze occur during beta-blockade and reverse on withdrawal |
| Strength | met | PRR 8 on a large co-report count |
| Consistency | met | Reproduced across the whole beta-blocker class |
| Specificity | partial | Shared across non-selective beta-blockers, not unique to propranolol |
| Biological gradient | met | Dose-related and worse with other rate-slowing or negative-inotropic drugs |
| Plausibility | met | Beta-1 block slows the SA/AV nodes; beta-2 block constricts bronchi |
| Coherence | met | Coheres with the labelled contraindication in asthma and routine heart-rate checks |
| Experiment | partial | Dechallenge (withdrawal) reverses both effects; no randomized trial |
| Analogy | met | Analogous to bradycardia and bronchospasm with other non-selective beta-blockers |
This page's own qualitative read, not an automated/citation-gated assessment.
✗ A large results-posting propranolol trial (in infantile haemangioma, NCT01056341) tracked bradycardia and recorded only a single serious event, in the highest-dose arm — consistent with how uncommon symptomatic bradycardia is in the populations studied rather than contradicting the mechanism.