For pharmacological information, see Beta blockers in 'Getting to know your drugs'.

No clear toxic dose has been identified except for propranolol where ingestions of more than 2 g are associated with seizures.

There are a number of important risk factors in beta blocker poisoning:

The presenting features include:

Ensure that there is an adequate airway and breathing. However, intubation and ventilation are usually only required with severe poisoning, where a decreased level of consciousness is multifactorial (hypoxia, hypotension, direct drug effect).

Coma and seizures are common with severe propranolol poisoning and will require early intervention.

Hypotension should be treated with a fluid bolus of 20 mL/kg of normal saline. Use:

This should be repeated if there is no response or only a partial response. Persistent hypotension will need to be treated with inotropes, see Inotropic support.

Serial ECGs and ECG monitoring should be done in all but minor poisonings with beta blockers. Bradycardia can be treated with atropine if there is hypotension, use:

Severe bradycardia with persistent hypotension may require temporary transvenous pacing.

Torsades de pointes may occur with sotalol poisoning and the QT interval should be measured regularly. Torsades de pointes should be treated with a 200 J DC shock and then isoprenaline or transvenous pacing, but magnesium should be avoided due to its potential to cause calcium channel blockade. In adults, use:

There is considerable controversy over inotropes in beta-blocker poisoning and advice from a clinical toxicologist should be obtained early. Although glucagon is often recommended there is no evidence to support its effectiveness, and there is rarely enough glucagon kept in hospitals to maintain treatment for over an hour. Recent animal evidence suggests vasopressors do not improve outcomes, so adrenaline, noradrenaline and vasopressin should be avoided in isolation. The following inotropes are recommended based on animal studies and anecdotal experience. In adults, use:

Vasopressors such as metaraminol or low-dose adrenaline may be useful in the short term if there is evidence of reduced systemic vascular resistance with the use of insulin or isoprenaline. However, they should not be used in patients with the poor perfusion typical of untreated beta blocker poisoning. In adults, use:

If the patient has a cardiac arrest, prolonged cardiopulmonary resuscitation should be undertaken (4 to 8 hours), as prior to the overdose these patients are usually healthy individuals. Cardiac assist devices and/or extracorporeal circulatory support should be considered if available.

Consider an initial dose of charcoal up to two hours after the estimated time of ingestion in severe poisoning if the patient has a protected airway. Use:

Caution: In the setting of beta blocker overdose, atropine should be administered prior to the insertion of a nasogastric tube to prevent further bradycardia due to vagal stimulation. Use:

Treat underlying hypoglycaemia, see below.

Persistent seizures seen in propranolol poisoning should initially be treated with benzodiazepines. For drug and dosing recommendations, see Anticonvulsant therapy.

Hypoglycaemia should be treated. Use:

Criteria for admission: All patients with deliberate self-poisoning or patients unintentionally ingesting more than the daily dose of beta blockers should be assessed initially and observed for at least six hours.