| For symptoms of overdose, see Overdose.Various extrapyramidal reactions to metoclopramide, usually of the dystonic kind, have been reported. Incidence of dystonic reactions, particularly in children and young adults, is increased if daily doses in excess of 0.5mg/kg body weight are used. Examples of dystonic reactions include: facial muscle spasm, trismus, bulbar type speech, rhythmic tongue protrusion, spasm of extra-ocular muscles (including oculogyric crises), unnatural positioning of head and shoulders and opisthotonos. There may also be a generalised increase in muscle tone. In most cases, the majority of these reactions occur within 36 hours of initiating treatment, they usually reverse within 24 hours of drug withdrawal. If necessary, dystonic reactions may be treated by use of an anticholinergic anti-parkinsonian drug, or a benzodiazepine. Tardive dyskinesia, occurring during prolonged treatment, has been reported, mainly in elderly patients; such patients should be regularly reviewed.Very rare occurrences of neuroleptic malignant syndrome have been reported. This syndrome is potentially fatal and comprises of hyperpyrexia, altered consciousness, muscle rigidity, autonomic instability and elevated levels of creatinine phosphokinase (CPK) and must be treated urgently (recognised treatments include dantrolene and bromocriptine). Metoclopramide should be stopped immediately if this syndrome occurs.Other side effects and approximate incidence:-Drowsiness (about 10%), restlessness (about 5%), unusual tiredness or weakness (about 10%).The following are less frequent or rare:Breast tenderness and swelling, constipation (less than 1%), changes in menstruation, depression, diarrhoea, dizziness (less than 1%), headache, nausea, skin rash, trouble sleeping, unusual dryness of mouth, unusual irritability and confusion. Depression has been reported extremely rarelyRaised serum prolactin levels have been observed during metoclopramide therapy: this may result in galactorrhoea, irregular periods and gynaecomastia.Extremely rarely cases of red cell disorders such as methaemoglobinaemia and sulphaemoglobinaemia have been reported, particularly at high doses of metoclopramide. If this occurs the drug should be withdrawn. Methaemoglobinaemia may be treated using methylene blueA small number of skin reactions such as urticaria, pruritus and oedema (including face oedema). Allergic reactions may also occur. Very rarely hypersensitivity, including anaphylaxis has been reported. | |