Electrolyte · Hyperkalemia treatment · Antidote
Calcium chloride
Indications
- Acute symptomatic hypocalcemia, including citrate effects in massive transfusion
- Low ionized calcium after cardiopulmonary bypass, often given to support contractility
- Hyperkalemia with ECG changes in arrest or peri-arrest (off-label)
- Calcium channel blocker or beta-blocker poisoning (off-label)
- Magnesium toxicity (off-label)
Dosing
| Where | Dose |
|---|---|
| Cardiac arrest | Calcium chloride: 1 g (10 mL of 10%) for hyperkalemia or calcium channel blocker overdose |
| Metabolic and electrolyte boluses | Calcium gluconate: 1–3 g IV over 2–5 min (stabilizes; repeat if ECG changes persist) |
| Metabolic and electrolyte boluses | Calcium chloride: 1 g via central line (three times the elemental calcium) |
| Unit conversions | Calcium (total): mg/dL ÷ 4 = mmol/L; ionized 1.1–1.3 mmol/L = 4.4–5.2 mg/dL |
| Unit conversions | Calcium gluconate 10%: 1 g = 4.65 mEq (93 mg) elemental calcium |
| Unit conversions | Calcium chloride 10%: 1 g = 13.6 mEq (272 mg) elemental calcium |
On the quick cards
Mechanism of action
Calcium chloride is fully ionized, so ionized Ca²⁺ rises at once, and per gram it carries three times the calcium of gluconate. Ca²⁺ entering heart and vascular muscle through L-type channels triggers calcium release from the sarcoplasmic reticulum and contraction, so raising extracellular Ca²⁺ supports contractility and tone when calcium is low or the channels are blocked. Higher extracellular Ca²⁺ also raises the threshold potential, restoring conduction in hyperkalemia without lowering potassium.
Pharmacology
- Cardiovascular: raises contractility and BP when ionized calcium is low (bypass, transfusion, CCB poisoning); with normal levels any gain is small and brief
- Cardiovascular: injection faster than 1 mL/min causes hypotension, bradycardia and cardiac syncope (label)
- Neuromuscular: ends tetany and laryngospasm and antagonizes magnesium
- Metabolic: each gram adds 13.6 mEq of chloride; repeated doses cause hyperchloremic acidosis
Pharmacokinetics
| Onset | Immediate; hyperkalemic ECG changes improve within 1–3 min |
|---|---|
| Duration | 30–60 min of membrane protection; ionized calcium starts falling again within 10 min of a bolus (Martin 1990), so CCB poisoning needs repeat doses or an infusion |
| Distribution | 99% of body calcium is in bone; serum calcium is about 50% ionized, 40% albumin-bound and 8–10% complexed (label) |
| Metabolism | None; it needs no liver, and gluconate matched it in anhepatic patients (Martin 1990) |
| Elimination | Calcium by glomerular filtration with tubular reabsorption (label); chloride by the kidney |
| Equivalence | 10 mL of 10% chloride (6.8 mmol) ≈ 30 mL of 10% gluconate |
Chemistry
- Calcium chloride dihydrate (CaCl₂·2H₂O, MW 147.0), an inorganic salt that dissociates completely, so pKa, lipid solubility and stereochemistry do not apply
- 10% is 100 mg/mL: 27 mg (1.4 mEq) of elemental calcium per mL, so 1 g gives about 272 mg (13.6 mEq), three times gluconate (label)
- 2,040 mOsm/L (label), about seven times plasma; pH 5.5–7.5; no preservative; up to 1,000 mcg/L of aluminum
- Very soluble, so it does not crystallize like gluconate, but it precipitates with bicarbonate (as calcium carbonate), phosphate and ceftriaxone
Adverse effects and cautions
In the one-pagers
- Electrolyte ImbalancesHyperkalemia: stabilize, shift, remove: Stabilize (ECG changes): calcium gluconate 10% 30 mL over 10 min; in arrest or peri-arrest, calcium chloride 10% 10 mL over 5 min (same calcium). Acts in about 3 min, lasts 30–60 min; repeat if changes persist.
- Abdominal, GI Bleeding, GU and Dialysis EmergenciesDialysis: access, hypotension, disequilibrium and uremia: Missed dialysis: uremia (lassitude, anorexia, falling mental acuity first, Merck), overload and hyperkalemia. Uremic encephalopathy reverses with dialysis and is an indication to start it (StatPearls abstract). Hyperkalemia treatment: electrolytes and acls-algorithms; NASEMSO gives calcium chloride 1 g IV/IO over 5 minutes when findings of
- Common EMS MedicationsGlucose, overdose and electrolytes: Calcium chloride 10%, electrolyte: High K with ECG changes, CCB OD, Mg toxicity: 1 g over 5 min (= 3 g gluconate); CCB 2 g: Digoxin toxicity, hypercalcemia; necrosis if it leaks
- Pediatric Assessment and EmergenciesPALS: arrest, bradycardia, tachycardia and IO access: Calcium chloride 10%: 20 mg/kg (0.2 mL/kg): low Ca²⁺, high K⁺, CCB toxicity
- Toxidromes and AntidotesCardiotoxic drugs: Calcium channel blockers: Calcium chloride 2 g or gluconate 6 g IV: Chloride: central line preferred
Practice Electrolyte Imbalances questions free26 exam-style questions with rationales on the topic where Calcium chloride comes up most. No account or download needed.
In the algorithms
Other electrolyte drugs
Practice free in your browser2,450+ exam-style questions with rationales. No account, no ads. Also free on the App Store and Google Play.
Sources
- FDA label: Calcium Chloride 10% (Hospira, 2026)
- Martin 1990 (calcium salts without a liver)
- AHA 2025 Guidelines, Part 10 (special circumstances)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow your local protocols and medical direction.