Other adverse events of sulphonylureas include uncommon sensitivity reactions-usually cutaneous-that are usually transient erythema multiforme is rare. Fever,jaundice and blood dyscrasias are very rare; some sulphonylureas can reportedly precipitate acute porphyria in predisposed individuals. In its heyday, chlorpropamide was notorious for causing unpleasant facial flushing after consuming small quantities of alcohol; photosensitivity has also been reported. Chlorpropamide could also increase renal sensitivity to antidiuretic hormone, occasionally causing water retention with hyponatraemia. In contrast, glibenclamide is credited with a mild diuretic action. Weight gain is regarded as a class effect of sulphonylurea therapy, typically amounting to 1-4 kg and stabilising after about 6 months. This weight gain, which is always unwelcome, is thought to reflect the anabolic effects of increased plasma insulin concentrations; some studies have suggested that reduced loss of calories as glucose in the urine may account for the majority of the weight gain.