Clinical trials on albendazole have shown that adverse effects occur only in a small percentage of patients and these are usually mild and transient. No significant differences were observed in the incidence of adverse effects in albendazole and placebo groups in controlled trials. These effects include epigastric pain, diarrhoea, headache, nausea, vomiting, dizziness, constipation, pruritus and dry mouth. Haematological and biochemical parameters remain unaltered following short-term treatment with albendazole, but rise in transaminase levels have been reported with long-term dosing.