Pharmacology · Class
Beta blockers !
Medicines that shield the heart from adrenaline: the heart beats slower and with less force, so it needs less oxygen.
Updated 2026-11-01
What they are
Antagonists of beta-adrenergic receptors. Some block β1 and β2 alike (non-selective), others mainly the cardiac β1 receptor (cardioselective). They are used in angina, after a heart attack, in heart failure, for heart-rate control and in several non-cardiac conditions.
Mechanism of action
Noradrenaline and adrenaline raise heart rate, contractility and AV conduction through β1 receptors, and β1 receptors in the kidney release renin. Blocking them slows the heart, lowers oxygen demand and reduces renin. Blocking β2 can narrow the airways and blunt the warning signs of hypoglycaemia.
Target: β1- and β2-adrenergic receptors
Drugs in this class
- PropranololA beta blocker that blocks adrenaline's action on the heart and elsewhere. Used for migraine prevention, tremor and…β-adrenergic receptors (β1 and β2)
- MetoprololA beta blocker that mainly acts on the heart (β1). It slows the heart rate and is used in angina, after a heart attack…β1-adrenergic receptor
- AtenololA β1-selective beta blocker cleared by the kidneys. Used for high blood pressure, angina and after a heart attack.β1-adrenergic receptor
- BisoprololA highly β1-selective beta blocker. Used for high blood pressure and, started low and raised slowly, for heart failure…β1-adrenergic receptor
- CarvedilolA beta blocker that also blocks α1 receptors, so it widens vessels. A key drug in heart failure with reduced ejection…β- and α1-adrenergic receptors
- EsmololAn ultra-short-acting, β1-selective beta blocker given by IV infusion. Its effect fades within minutes of stopping it.β1-adrenergic receptor
- LabetalolA combined α1 and β blocker, by mouth or IV. Used for severe hypertension and is a first choice for high blood…β- and α1-adrenergic receptors
- SotalolA beta blocker that also blocks potassium channels and lengthens the QT. Used for serious arrhythmias; it is started…hERG potassium channel (IKr) and β-adrenergic receptors
- NebivololA β1-selective beta blocker that also promotes nitric oxide release from vessel walls, adding vasodilation. Used for…β1-adrenergic receptor
Others in the class
- Atenolol
- Bisoprolol
- Carvedilol
- Nebivolol
- Esmolol
- Labetalol
Test yourself
Think of the answer, then tap the question to see it.
Why is a non-selective beta blocker risky in a patient with asthma?
β2 receptors relax bronchial smooth muscle. Blocking them can trigger bronchospasm and reduce the response to inhaled β2 agonists.
Which beta blockers have shown lower mortality in heart failure with reduced ejection fraction?
Bisoprolol, carvedilol and metoprolol succinate (the extended-release form).
Which hypoglycaemia warning sign usually persists despite beta blockade, and why?
Sweating, because it is driven by sympathetic cholinergic fibres, not by β receptors. Tachycardia and tremor are blunted.
Why should a beta blocker not be stopped abruptly?
Receptors up-regulate during treatment; sudden withdrawal exposes them to catecholamines, causing rebound tachycardia, hypertension, angina or infarction.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Propranolol: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); Metoprolol: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); DailyMed - METOPROLOL SUCCINATE- metoprolol succinate er tablets tablet, film coated, extended release (DailyMed (U.S. National Library of Medicine), 2026).
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Representative model, for educational purposes only.