Reglan - Drug Interactions

Drug interactions are complex and sometimes unpredictable when a drug is first introduced (despite exhaustive testing during clinical trials). Doctors and pharmacists devote a great deal of time to studying issues of drug interactions, not only with each other but with substances such as alcohol, caffeine, nicotine and even herbs and herbal extracts. This is a primary reason why patients are asked to provide a full medical history when they begin seeing a physician.

When taking medications with documented dangerous side effects such as Reglan, it is vital that the patient be forthcoming about any and all substances they may be taking, including herbs and herb supplements from a health food store (which contain many of the same compounds as prescription drugs) and their use of alcohol, caffeine and tobacco.

Reglan and Other Prescription Drugs

Fortunately, there is little shortage of knowledge regarding Reglan (metoclopramide). The primary interaction risk involves patients who are already on medication for a movement disorder, such as those prescribed for Parkinson's disease or dystonia. Reglan by itself is known to cause the movement disorder tardive dyskinesia in some patients. Taking it with other medications is also known to increase the effects of several other prescription drugs, including:

  • Acetaminophen (Tylenol and other non-aspirin analgesics)
  • Antispasmodics (belladonna alkaloids such as atropine, hyocyamine and scopolamine)
  • Cimetidine
  • Cyclosporine and digoxin (anti-rejection drugs for transplant patients)
  • MAOI medications
  • Antidepressants
  • Levodopa (treatment for Parkinson's Disease)
  • Narcotic analgesics (opiate painkillers such as Vicodin)
  • Tetracycline
  • Any kind of tranquilizer (including sleep medications)

In addition, insulin-dependent diabetics may need to adjust their insulin dosage as Reglan affects the digestive process and therefore the absorption of carbohydrates into the system.

Reglan and Over-The-Counter Medications

In general, what is applicable to Reglan and prescription drugs also applies to over-the-counter (OTC) medications as well. OTC medications have the same ingredients as their prescription counterparts, but in lower concentrations. It is important for a patient to discuss any OTC medications they normally take with their doctor before receiving treatment with Reglan.


  1. Griffin, R. Morgan. "The Heartburn-Tobacco Connection."
  2. Shaffer, Douglas et. al. "Tardive Dyskinesia and Metoclopramide Use: Effects of Cisapride Market Withdrawal." Journal of the American Pharmacists Association vol. 44 no. 6 (2004).