Drug Interaction Report

Magnesium and Nifedipine: Interaction Details

A pharmacist-reviewed analysis of the Magnesium and Nifedipine interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Nifedipine

Adalat® Adalat® CC Afeditab CR Afeditab® CR Nifedical® XL Nifeditab® CR Procardia Procardia®
+

Magnesium

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Moderate
Can be significant — usually manageable with monitoring.
How we grade severity & evidence

Severity levels

  • Contraindicated: These should generally not be used together.
  • Major: Potentially serious — often needs a change or close monitoring.
  • Moderate: Can be significant — usually manageable with monitoring.
  • Minor: Usually limited clinical impact.

Evidence grades

  • Established: Well documented — supported by controlled studies or strong clinical data.
  • Probable: Good supporting evidence, though not definitively proven.
  • Suspected: Some evidence suggests this interaction, but it is not well established.
  • Possible: Limited or conflicting evidence; the interaction may occur.
  • Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Of 22 documented Magnesium interactions, 20 are rated moderate — including this one.
Onset
rapid
Evidence
probable
Severity
Moderate

What happens

Hypotension

Interaction Deep Dive

When used to retard premature labor, concomitant NIFEdipine and magnesium has been reported to cause exacerbated hypotensive and neuromuscular blockade effects123.

Why it happens (mechanism)

Unknown

Literature reports

2 reports — tap to read

a) NIFEdipine administered with magnesium may cause exacerbated hypotensive and neuromuscular blockade effects. NIFEdipine 60 mg initially and then 20 mg every eight hours was combined with intravenous magnesium 500 mg to suppress labor. The patient developed jerky movements, swallowing difficulty, paradoxical respirations and neck muscle weakness, which resolved upon discontinuation of the magnesium 1.

b) Another study reported two cases of women with hypertension during pregnancy that did not resolve with methyldopa and magnesium, so oral NIFEdipine 10 mg was administered. Within 45 minutes, both patients' blood pressure drastically dropped, indicating a possible induction of excessive hypotension by the combination of NIFEdipine and magnesium and/or methyldopa 2.

Common questions

Can I take Magnesium and Nifedipine together?

Hypotension Always confirm with your pharmacist or prescriber before making any change.

How serious is the Magnesium and Nifedipine interaction?

It is rated moderate. Can be significant — usually manageable with monitoring.

How quickly could this interaction happen?

The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.

How strong is the evidence for this interaction?

The evidence is graded "probable". Good supporting evidence, though not definitively proven.

Questions for your pharmacist

  • Does my dose of Magnesium or Nifedipine need adjusting while I take them together?
  • What symptoms should prompt me to call you or my prescriber right away?
  • Does the timing of my doses matter for this combination?
  • Is there anything you'd monitor while I'm on both?

References (3)

  1. Snyder SW & Cardwell MS: Neuromuscular blockade with magnesium sulfate and nifedipine. Am J Obstet Gynecol 1989; 161:35-36. PubMed
  2. Waisman GD, Mayorga LM, Camera MI, et al: Magnesium plus nifedipine: Potentiation of hypotensive effect in preeclampsia?. Am J Obstet Gynecol 1988; 159:308-309. DOI
  3. Ben-Ami M, Giladi Y, & Shalev E: The combination of magnesium sulphate and nifedipine: a cause of neuromuscular blockade. Br J Obstet Gynaecol 1994; 101:262-263. PubMed
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Nifedipine

Keep reading about Nifedipine

All Nifedipine interactions (325) Nifedipine drug information
Also serious with: Rifabutin Primidone Rifapentine Rifampin
Magnesium

Keep reading about Magnesium

All Magnesium interactions (22)
Also serious with: Baloxavir Marboxil Dolutegravir
Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Nifedipine + Activated Charcoal American Hellebore American Mistletoe Beer Coca Coleus Grapefruit Siberian Cocklebur + 265 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.