Taking too much of a beta blocker such as metoprolol or propranolol slows the heart and weakens its pumping, which leads to bradycardia, low blood pressure and shock. Propranolol can also cause seizures and a wide QRS, and low blood sugar is common in children.
Key symptoms
- Dizziness, weakness or fainting
- Confusion or drowsiness
- Shortness of breath or wheeze, mostly in people with asthma
- Seizures, mainly with propranolol
What you find on exam
- Slow pulse, often under 50 per minute
- Low blood pressure with cool, pale skin
- Level of consciousness and pupils
- Crackles in the lungs from heart failure
Tests
- 12-lead ECG: heart block, long PR, wide QRS
- Blood glucose right away and repeated
- Electrolytes, kidney function and a blood gas
- Acetaminophen and salicylate levels to look for co-ingestion
Treatment basics
- Airway, oxygen, cardiac monitor and IV access; call poison control
- IV fluids and atropine for bradycardia, often with limited effect
- IV glucagon bolus then infusion; calcium can help
- High-dose insulin with dextrose, plus vasopressors such as epinephrine
- Transcutaneous pacing if drugs fail; activated charcoal only if the airway is safe
Red flags
- Systolic blood pressure under 90 with altered mental status
- Wide QRS complex or new heart block on the ECG
- Seizures or low blood sugar
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Related guides
Sources: NASEMSO National Model EMS Clinical Guidelines; National EMS Education Standards (2021). Written by Making Synapses. Making Synapses is not affiliated with these organizations.