Reglan Side Effects. Severity: Major. If any of the following side effects occur while taking metoclopramide, check with your doctor immediately:
Abdominal or stomach pain or tenderness
chills
clay colored stools
convulsions (seizures)
dark urine
difficulty with breathing
difficulty with speaking or swallowing
dizziness or fainting
fast or irregular heartbeat
fever
general feeling of tiredness or weakness
headache (severe or continuing)