The following adverse reactions are from the cumulative post-marketing experience with metoclopramide tablets. Since the reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
CNS Effects: Restlessness, drowsiness, fatigue, and lassitude occur in approximately 10% of patients receiving the most commonly prescribed dosage of 10 mg four times a day. Insomnia, headache, confusion, dizziness, or depression with suicidal ideation occurs less frequently. The incidence of drowsiness is greater at higher doses. There are isolated reports of seizures without clear-cut relationship to metoclopramide. Rarely, hallucinations have been reported.
Extrapyramidal Syndromes (EPS):
Acute dystonic reactions, the most common type of EPS associated with metoclopramide, occur in approximately 0.2% of patients (1 in 500) treated with 30 to 40 mg of metoclopramide per day. Symptoms include involuntary movements of limbs, facial grimacing, torticollis, oculogyric crisis, rhythmic protrusion of tongue, bulbar type of speech, trismus, opisthotonus (tetanus-like reactions), and rarely, stridor and dyspnea possibly due to laryngospasm; ordinarily these symptoms are readily reversed by diphenhydramine [see Warnings and Precautions (5.1)].
Drug-induced Parkinsonian-like symptoms may include bradykinesia, tremor, cogwheel rigidity, mask-like facies [see Warnings and Precautions (5.2)].
Tardive dyskinesia is most frequently characterized by involuntary movements of the tongue, face, mouth, or jaw, and sometimes by involuntary movements of the trunk and/or extremities; movements may be choreoathetotic in appearance. Motor restlessness (akathisia) may include inability to sit still, pacing, and foot tapping. These symptoms may disappear spontaneously or respond to a reduction in dosage.
Neuroleptic Malignant Syndrome: Rare occurrences of Neuroleptic Malignant Syndrome (NMS) have been reported [see Warnings and Precautions (5.3)].
Endocrine Disturbances: Galactorrhea, amenorrhea, gynecomastia, and impotence secondary to hyperprolactinemia. Fluid retention secondary to transient elevation of aldosterone.
Cardiovascular: Hypotension, hypertension, supraventricular tachycardia, bradycardia, fluid retention, acute congestive heart failure, possible AV block.
Gastrointestinal: Nausea, bowel disturbances, primarily diarrhea.
Hepatic: Rarely, cases of hepatotoxicity characterized by such findings as jaundice and altered liver function tests, when metoclopramide was administered with other drugs with known hepatotoxic potential.
Renal: Urinary frequency and incontinence.
Hematologic: A few cases of neutropenia, leukopenia, or agranulocytosis, generally without clear-cut relationship to metoclopramide. Methemoglobinemia in adults and especially with overdosage in neonates. Sulfhemoglobinemia in adults.
Allergic Reactions: A few cases of rash, urticaria, or bronchospasm, especially in patients with a history of asthma. Rarely, angioneurotic edema, including glossal or laryngeal edema.
Miscellaneous: Visual disturbances. Porphyria.