Metoclopramide is widely used as an antiemetic and a prokinetic agent. Both the antiemetic properties and side effects of the drug are the result of dopamine receptor antagonism within the central nervous system. Therapeutic doses of metoclopramide can produce adverse effects. A 5-month-old girl was referred to our emergency department with the pre-diagnosis of afebrile convulsion. In her medical history, she was mistakenly given 2 mg/kg metoclopramide within a 24 h period, after which she became hypertonic and exhibited intermittent opisthotonos. Complete blood count, electrolytes, liver and renal function tests, blood gas analysis, and urinalysis were all within normal limits. Electroencephalogram, brain CT and cerebrospinal fluid examination were normal. Metoclopramide treatment was discontinued and she was treated with biperiden, which led to an improvement in symptoms after 15 minutes and complete remission in 60 minutes. Intermittent opisthotonos may be confused with convulsion in infant and thus lead to an unnecessary hospital admission. Physicians should be aware that metoclopramide is widely used in the pediatric population and children are susceptible to the side effects of metoclopramide and the side effects may present as “intermittent opisthotonos” as observed in our patient.