Propranolol !
A beta blocker that blocks adrenaline's action on the heart and elsewhere. Used for migraine prevention, tremor and portal hypertension.
Updated 2026-11-01
The figure shows propranolol in the human β2 receptor (fused to a T4 lysozyme for crystallisation); propranolol blocks β1 in the same way.
Mechanism of action
Propranolol blocks β1 and β2 receptors alike. At β1 it slows the heart, reduces contractility and lowers renin release. At β2 it can narrow the airways and reduces splanchnic vasodilation, which lowers portal blood flow. It is lipophilic and enters the brain, which explains its use in migraine and tremor and some of its side effects.
- Propranolol blocks β1 and β2 receptors
- Heart rate, contractility and renin fall (β1)
- Splanchnic flow and portal pressure fall (β2)
- Less cardiac oxygen demand and fewer adrenergic symptoms
Pharmacokinetics
- Absorption
- Well absorbed by mouth, but with a large first-pass effect in the liver
- Distribution
- Lipophilic: crosses the blood-brain barrier
- Metabolism
- Extensive liver metabolism
- Elimination
- As metabolites in the urine
- Half-life
- About 3 to 6 hours for the immediate-release form
Indications
- Migraine prevention Migraine →
- Prevention of variceal bleeding in portal hypertension Portal hypertension →
- Control of adrenergic symptoms in hyperthyroidism (tachycardia, tremor, anxiety) Graves disease (hyperthyroidism) →
- High blood pressure (not a first choice today) Arterial hypertension →
- Essential tremor
Adverse effects
Common
- Tiredness and exercise intolerance
- Bradycardia and dizziness
- Cold hands or Raynaud-type poor circulation
- Sleep disturbance and vivid dreams
Contraindications
- Asthma
- Marked bradycardia or second- or third-degree AV block without a pacemaker
- Overt heart failure or cardiogenic shock
Key interactions
- Verapamil or diltiazem
- Severe bradycardia, AV block and hypotension
- Insulin or sulfonylureas
- Hypoglycaemia warning signs are masked and recovery may be slower
- Adrenaline (epinephrine)
- Unopposed alpha effect with sharp hypertension, and a weaker response in anaphylaxis
- Cimetidine
- Higher propranolol levels
What is monitored
- Heart rate and blood pressure
- Breathing symptoms in lung disease
- Blood glucose in people with diabetes
Test yourself
Think of the answer, then tap the question to see it.
Why is propranolol useful in portal hypertension?
β1 blockade lowers cardiac output and β2 blockade leaves splanchnic vasoconstriction unopposed, so portal inflow and pressure fall, lowering the risk of variceal bleeding.
Which property of propranolol explains its use in migraine and tremor, and also nightmares?
Its lipophilicity: it crosses the blood-brain barrier and acts on the central nervous system.
Why is propranolol used in thyrotoxicosis even though it does not treat the thyroid?
Many symptoms (tachycardia, tremor, anxiety, sweating) are adrenergic; blocking β receptors controls them while the gland itself is treated.
A patient on propranolol has anaphylaxis and responds poorly to adrenaline. Why?
β2 blockade blunts adrenaline's bronchodilator and vasodilating effects, and its unopposed alpha action can cause marked hypertension.
Related drugs
Related conditions
← Back to the class: Beta blockers
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - PROPRANOLOL HYDROCHLORIDE tablet (DailyMed (U.S. National Library of Medicine), 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); Bleeding esophageal varices: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2026); Hyperthyroidism: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2026).
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Representative model, for educational purposes only.