Drug Interaction Report

Metoclopramide Injection and Cimetidine: Interaction Details

A pharmacist-reviewed analysis of the Metoclopramide Injection and Cimetidine 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

Cimetidine

Tagamet
+

Metoclopramide Injection

Gimoti Metozolv Pileran Reglan Reglan® I.V.
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
Minor
Usually limited clinical impact.
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 247 documented Metoclopramide Injection interactions, 4 are rated minor — including this one.
Onset
delayed
Evidence
probable
Severity
Minor

What happens

Decreased cimetidine effectiveness

Interaction Deep Dive

Two studies have shown that concurrent administration of metoclopramide and cimetidine may result in decreased cimetidine bioavailability12.

Why it happens (mechanism)

Decreased absorption

Literature reports

3 reports — tap to read

a) Metoclopramide 14 mg reduced the bioavailability of cimetidine 400 mg by 22% according to the area under the plasma concentration-time curve (AUC), in 8 subjects in a crossover study. Since no change in the half-life or renal clearance was associated with the reduced excretion of cimetidine in the urine, the gastrointestinal absorption of cimetidine appears reduced. The use of oral or intravenous metoclopramide in conjunction with cimetidine may necessitate an increase in cimetidine dose 1.

b) When oral metoclopramide 20 mg was administered 2 hours following the administration of oral cimetidine 400 mg, small and insignificant alterations in the pharmacokinetics of cimetidine were evident 2.

c) Cimetidine has 2 distinct peak levels when the drug is given orally, under fasting conditions 3. If the second peak level was caused by absorption of cimetidine at a limited site in the intestine, the increased motility from metoclopramide would reduce this second-phase absorption.

Common questions

Can I take Metoclopramide Injection and Cimetidine together?

Decreased cimetidine effectiveness Always confirm with your pharmacist or prescriber before making any change.

How serious is the Metoclopramide Injection and Cimetidine interaction?

It is rated minor. Usually limited clinical impact.

How quickly could this interaction happen?

The documented onset is "delayed". Effects tend to build up gradually over days to weeks.

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 Metoclopramide Injection or Cimetidine 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. Gugler R, Brand M, & Somogyi A: Impaired cimetidine absorption due to antacids and metoclopramide. Eur J Clin Pharmacol 1981a; 20:225-228. PubMed
  2. Barzaghi N, Crema F, Mescoli G, et al: Effects on cimetidine bioavailability of metoclopramide and antacids given two hours apart. Eur J Clin Pharmacol 1989; 37:409-410. DOI
  3. Kanto J, Allonen H, & Mantyla J: The effect of metoclopramide and propantheline on the gastrointestinal absorption of cimetidine. Br J Clin Pharmacol 1981; 11:629-630. DOI
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Cimetidine

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Metoclopramide Injection

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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:

Cimetidine + Activated Charcoal Pu-erh Tea St. John's Wort Adrafinil African Wild Potato Banderol Beer Bitter Melon + 87 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.