Metoclopramide Side Effects: What to Expect and When to Call Your Doctor

Metoclopramide (brand name Reglan) is an effective medication, but it carries one of the most serious safety warnings of any commonly prescribed drug: a FDA boxed warning for tardive dyskinesia, a potentially irreversible movement disorder. Understanding the full side-effect profile — from mild drowsiness to rare but serious complications — is essential for any patient taking this medication.

The FDA Boxed Warning: Tardive Dyskinesia (TD)

Tardive dyskinesia is the most serious potential side effect of metoclopramide. It is a movement disorder characterized by involuntary, repetitive muscle movements — especially of the face, tongue, and extremities.

Key facts about tardive dyskinesia from metoclopramide:

• Can be permanent and irreversible even after stopping the drug
• There is no known treatment for TD once it develops
• Risk increases with longer duration of use and higher cumulative doses
• Approximately 20% of patients took metoclopramide for longer than 12 weeks (per FDA analysis) — a practice that significantly elevates risk
• The FDA added a black box warning in 2009, requiring all metoclopramide manufacturers to warn about TD with chronic or high-dose use

Signs of tardive dyskinesia to watch for include: lip smacking, puckering, chewing movements, tongue protrusion, blinking, and uncontrolled movements of arms or legs. If you notice any of these, stop taking metoclopramide and contact your doctor immediately.

Common Side Effects (More Than 10% of Patients)

These side effects are expected in roughly 1 in 10 patients or more:

• Restlessness (akathisia): A feeling of inner motor restlessness or needing to keep moving. This is often mistaken for anxiety.
• Drowsiness/somnolence: Can affect up to 70% of patients at higher doses. Do not drive or operate machinery if drowsiness occurs.
• Fatigue and lassitude: Low energy and general tiredness are common, especially in the first few days of treatment.

Other Common Side Effects (1–10% of Patients)

• Headache
• Dizziness
• Insomnia
• Confusion (especially in elderly patients)
• Depression — metoclopramide can worsen or cause depression, including with suicidal ideation. Report mood changes to your doctor.

Serious Extrapyramidal Side Effects (Call Your Doctor Immediately)

Beyond tardive dyskinesia, metoclopramide can cause other movement-related (extrapyramidal) side effects:

• Acute dystonic reactions: Involuntary muscle contractions, facial grimacing, twisting of the neck (torticollis). More common in children and adults under 30. Usually reversible with diphenhydramine (Benadryl) IV/IM.
• Parkinsonian symptoms: Tremor, rigidity, slowness (bradykinesia), or mask-like face. Usually develop within the first 6 months. Avoid metoclopramide in patients with Parkinson's disease — it will worsen symptoms.
• Neuroleptic Malignant Syndrome (NMS): Very rare but life-threatening. Signs include very stiff muscles, high fever, sweating, confusion, fast or uneven heartbeat, and tremors. Seek emergency care immediately.

Other Serious Side Effects

• Elevated prolactin: Long-term use can elevate prolactin levels, causing breast swelling, unexpected breast milk production (galactorrhea), menstrual irregularities, or reduced sexual function in both men and women.
• High blood pressure: IV metoclopramide can release catecholamines and raise blood pressure. Caution in patients with hypertension or on MAOIs.

Who Is at Highest Risk for Side Effects?

Some groups face significantly higher risk for serious side effects:

• Elderly patients: Higher risk for TD, confusion, and sedation. Listed on AGS Beers Criteria as potentially inappropriate.
• Elderly women: Highest risk group for tardive dyskinesia specifically.
• People with diabetes: Also at elevated TD risk.
• Children and young adults under 30: Higher risk for acute dystonic reactions; reglan is not recommended for pediatric use.
• CYP2D6 poor metabolizers: Eliminate the drug more slowly, increasing exposure and risk of side effects.

When to Call Your Doctor or Go to the ER

Call your doctor right away if you experience: uncontrolled muscle movements (especially in the face or tongue), muscle stiffness, tremors, mood changes, or signs of depression.

Go to the emergency room if: you have very stiff muscles with high fever and confusion (signs of NMS), difficulty breathing, or a severe allergic reaction.

For information on how metoclopramide interacts with other medications, see our guide on Metoclopramide Drug Interactions. If you need help finding metoclopramide at a pharmacy near you, visit medfinder.