Nausea and vomiting occur frequently during the first trimester of pregnancy, affecting 50-70% of pregnant women. 1-4 A peak is observed between weeks 10 and 16 of gestation, and most symptoms disappear by the 20th week. 4-6 In 0.5-2% of pregnancies, nausea and vomiting are persistent and severe and are referred to as hyperemesis gravidarum (HG). 2,7 HG is diagnosed by the presence of weight loss ≥5% of prepregnancy weight, ketonuria, hypokalemia, dehydration, or nutritional deficiencies. 1,7 The etiology of HG is multifactorial, and HG may lead to maternal and fetal complications. 7-11 HG treatment must be provided quickly and aggressively to prevent complicaBackground: In 1998, a protocol consisting of droperidol/diphenhydramine combination was established at Hospital Sainte-Justine to treat hyperemesis gravidarum.