🤰 Magnesium Sulfate in Labor: NCLEX Uses, Toxicity Signs & Nursing Interventions
Magnesium sulfate (MgSO₄) is a high-alert drug used in labor and delivery — most commonly to prevent seizures in preeclampsia and manage preterm labor. Due to its narrow therapeutic window and serious side effects, it is tested often on NCLEX pharmacology and OB nursing sections.
This blog gives you the signs, dosing, monitoring, and antidote info you need — with a signature KOTC visual.
👩⚕️ When Is Magnesium Sulfate Used?
| Indication | NCLEX Relevance |
|---|---|
| Preeclampsia | Prevents seizures (eclampsia) |
| Eclampsia | Stops active seizures |
| Preterm Labor | Relaxes uterus to stop contractions |
⚠️ Signs of Magnesium Toxicity
| System | Symptoms |
|---|---|
| Neuro | ↓ DTRs, lethargy |
| Respiratory | ↓ Respiratory rate (<12/min) |
| Cardiac | Bradycardia, hypotension |
| Renal | ↓ Urine output (<30 mL/hr) |
| Other | Warmth, flushing, progressing to toxicity |
🧪 Lab Monitoring
| Test | Normal Range | Toxic Range |
|---|---|---|
| Serum Magnesium | 4–7 mEq/L (therapeutic in OB) | >7 mEq/L |
| Reflexes | 2+ normal | 0 = toxicity |
| Urine Output | >30 mL/hr | <30 = HOLD drug |
🧠 NCLEX-Style Question
A patient on IV magnesium sulfate has DTRs 0, RR 10, and urine output 25 mL/hr. What is your priority action?
✅ Answer: Stop the infusion and prepare calcium gluconate.
🧯 Antidote for Magnesium Toxicity
Calcium Gluconate — always keep it at bedside if your patient is on mag.
Dose: 10 mL of 10% calcium gluconate IV over 10 minutes (as ordered).
💡 Mnemonic: “MAG SLOW”
M – Monitor reflexes
A – Assess RR and urine output
G – Give antidote if toxic
S – Seizure prevention
L – Lethargy = early toxicity
O – Output <30 = risk
W – Weak reflexes = STOP infusion
📲 Study OB Pharmacology with King of the Curve
📉 Drug visuals for labor & delivery
🎯 Toxicity signs in timed NCLEX Qs
💊 OB medication mnemonics
Find more at kingofthecurve.org/studyscience
🏁 Final Thoughts
Magnesium sulfate is life-saving, but dangerous if not monitored closely. The NCLEX expects you to know the warning signs, when to intervene, and what to give — now you do.
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