⚠️ Magnesium Toxicity: NCLEX Warning Signs & Interventions
Magnesium sulfate is often used to prevent seizures in preeclampsia, but can quickly become toxic — especially in patients with renal impairment.
The NCLEX loves this drug because it overlaps OB, med-surg, and pharmacology.
This blog breaks down the warning signs, lab ranges, nursing actions, and antidote — all supported with a King of the Curve visual.
📊 Magnesium Sulfate – NCLEX Chart
| Use | Prevent seizures in preeclampsia |
|---|---|
| Therapeutic Range | 4–7 mEq/L |
| Toxic Range | Greater than 7 mEq/L |
| Antidote | Calcium gluconate |
| Excretion | Renal — monitor urine output |
| Signs of Toxicity | Loss of deep tendon reflexes, ↓ RR, ↓ LOC, hypotension |
| Check Before Dose | Patellar reflex present and RR > 12/min |
🧠 NCLEX Tip: Reflexes Go First
If you can’t elicit a patellar reflex, the next dose should be held and the provider notified.
This is usually the first sign of magnesium toxicity.
🩺 Nursing Actions
Monitor reflexes hourly
Keep calcium gluconate at bedside
Track respiratory rate and O₂ saturation
Assess urine output regularly
Stop infusion and call provider if symptoms appear
💡 Mnemonic: “M-A-G SAFE”
| M | Monitor reflexes and respiratory rate |
|---|---|
| A | Assess urine output |
| G | Give slowly IV (never IV push) |
| S | Signs: ↓ RR, ↓ DTRs, lethargy |
| A | Antidote = Calcium gluconate |
| F | Flush kidneys (maintain hydration) |
| E | Evaluate every hour |
📲 Master OB Emergencies with King of the Curve
👶 Preeclampsia drug simulation sets
📊 Toxicity quiz banks
🧪 OB pharmacology visuals
Study smarter at kingofthecurve.org/studyscience
🏁 Final Thoughts
Magnesium sulfate can go from therapeutic to toxic quickly.
The NCLEX wants to know you’ll act fast — and prevent respiratory arrest by recognizing subtle neuro signs first.
Frequently Asked Questions (FAQs)
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