Chloramphenicol may cause marrow toxicity in the infant. Androgens cause masculinization of the female infant and precocious puberty in the male. Amiodarone is heavily iodinated resulting in iodine toxicity. The excessive uptake of iodine by the thyroid gland may result in inhibition of thyroid hormone synthesis resulting in hypothyroidism, occurring in up to 10% of patients, or excessive thyroid hormone production and hyperthyroidism. Cholestatic jaundice is a recognized side-effect of a number of drugs and these should be avoided in patients with underlying liver disease. Metformin should be avoided in liver impairment due to an increased risk of lactic acidosis. It is the sulphonylurea oral hypoglycaemics that cause obstructive jaundice Methyldopa causes hepatitis. An idiosyncratic reaction is an unexpected and unusual sensitivity exhibited by an individual to a particular drug.