Effectiveness of olanzapine for hyperemesis gravidarum in individuals without a psychiatric history: a case report

BACKGROUND: Hyperemesis gravidarum (HG) is characterized by severe nausea and vomiting during pregnancy, and can markedly impair quality of life as well as cause maternal and fetal complications. Although a stepwise treatment strategy with antiemetics and nutritional support is commonly used, some cases remain refractory. Olanzapine, an atypical antipsychotic, has shown potential benefit in HG, although most reports involve patients with psychiatric comorbidities. We describe a patient with persistent HG in late gestation without psychiatric history, in whom adjunctive olanzapine was temporally associated with improvement in nausea and vomiting symptoms. CASE PRESENTATION: A 42-year-old woman (Gravida 2, Para 0) conceived through frozen-thawed embryo transfer and was diagnosed with HG at gestational week 8. Despite intravenous fluids and metoclopramide, symptoms persisted, and she was hospitalized at 32 weeks due to poor maternal weight gain and fetal growth restriction. On admission, her nausea was severe (Numerical Rating Scale [NRS]: 10), with a Pregnancy-Unique Quantification of Emesis and Nausea (PUQE-24) score of 15 and persistent vomiting up to 18 episodes/day. Despite no prior psychiatric history, she developed depressive symptoms during pregnancy. Olanzapine was started at 2.5 mg/day and titrated to 10 mg/day by 35 weeks; total parenteral nutrition was initiated concurrently. By 35 weeks, her nausea improved (NRS: 10/10 to 3.5/10; PUQE-24: 15 to 9) and vomiting decreased to 9 episodes/day. A cesarean section was performed at 35 weeks and 2 days owing to acute pulmonary edema. A 2,160-g female infant was delivered with Apgar scores of 2, 4, and 5. The neonate was admitted to the neonatal intensive care unit due to transient respiratory distress (ventilation: 2 days; oxygen: 10 days), with a normal brain MRI prior to discharge and no evidence of hypoxic–ischemic encephalopathy. Maternal gastrointestinal symptoms resolved immediately after delivery. CONCLUSIONS: This case highlights the potential role of olanzapine in refractory HG management, even in the absence of pre-existing psychiatric comorbidities. It also underscores the importance of early nutritional intervention and multidisciplinary management, particularly when prolonged symptoms contribute to declining quality of life and depressive affect. Further case reports are required to confirm this therapeutic effect of olanzapine.