Nearly all respondents on bmj.com listed Kawasaki disease in the differential diagnosis, even though the duration of illness was only five days. One criterion of Kawasaki disease is fever for 10 days, but intravenous immunoglobulin has been shown to reduce the risk of coronary damage definitely only if administered by day 10.1 Later administration has not been so thoroughly evaluated, and intravenous immunoglobulin may be more effective when given within 5 days than between 5 and 10 days.2 Thus the dilemma when confronted with a febrile child is at what point …