Capillary leak syndrome with imiquimod (ALDARA Cream): A 56-year old man applied imiquimod (ALDARA 5% cream) a cream licensed for external anigenital warts to numerous actinic keratoses in the forehead region three times a week. Twelve days after starting the treatment, he was admitted to hospital because of chest pain, nausea and vomiting and diagnosed as having "acute coronary syndrome". He presented with generalised oedema of the arms and legs, hypoproteinaemia (24 g/l) and a marked rise in the red blood cell count (7.7 million/µl), haemoglobin concentration (23.7 g/dl) and haematocrit (68%). After a repeated blood-letting and several infusions of human albumin, the haemoglobin fell temporarily to 8 g/dl. A myeloproliferative disease was excluded. After nine days the patient was discharged in good condition. He resumed the local therapy with imiquimod. About two months later he was again admitted with abdominal pain, nausea, excessive sweating and dyspnoea. Haemoconcentration and marked muscle and skin oedema finally led to the diagnosis of "leakage syndrome after topical use of imiquimod". Within 24 hours, he showed a fluid retention of about 20 l and developed rhabdomyolysis with multiorgan failure. With intensive care treatment including ventilation, haemodialysis and blood transfusions, he finally recovered (NETZWERK report 13.028). The capillary leak syndrome is characterized by sudden and temporarily increased capillary permeability with leakage of fluid and protein into the surrounding tissue, haemoconcentration (pseudo-raised erythrocyte count) and hypoalbuminaemia. The pathogenesis of this rare disease that occurs episodically is unclear. The syndrome has also been described in critically ill patients and in association with different drugs, for example the antimetabolite gemcitabine (GEMZAR) and interferons. The Federal Institute for Medicines and Medical Devices has documented one other report of increased capillary permeability with generalised oedema, acute renal failure and chest pain in association with the - non-licensed - use of imiquimod in actinic keratosis. At present, the authority can neither exclude nor confirm a duplicate report (BfArM: letter of 22nd Dec. 2003). Other severe systemic consequences of the topical agent have been described (a-t 2003; 34: 23).