An overdose of a calcium channel blocker such as amlodipine, diltiazem or verapamil causes low blood pressure, a slow heart rate and shock, while the patient often stays alert at first. Extended-release pills can cause delayed and prolonged toxicity, and high blood sugar is a typical clue.
Key symptoms
- Dizziness, weakness or fainting
- Nausea and vomiting
- Confusion as blood pressure falls
- Shortness of breath from fluid in the lungs
What you find on exam
- Low blood pressure, often severe
- Slow pulse with diltiazem or verapamil; fast pulse is possible with amlodipine
- Cool skin, slow capillary refill, low urine output
- Crackles in the lungs
Tests
- 12-lead ECG: bradycardia, heart block, junctional rhythm
- Blood glucose: high sugar suggests severity
- Electrolytes, kidney function, lactate and blood gas
- Acetaminophen and salicylate levels for co-ingestion
Treatment basics
- Airway, oxygen, cardiac monitor, IV access; call poison control
- IV fluid bolus and atropine for bradycardia
- IV calcium chloride or calcium gluconate
- High-dose insulin with dextrose and potassium checks, plus vasopressors
- Pacing, activated charcoal or whole bowel irrigation and ECMO in selected cases
Red flags
- Persistent hypotension despite fluids
- Heart block or very slow rate
- Ingestion of extended-release pills, even with normal early vital signs
Practice it in Making Synapses
Making Synapses cases
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.