VOMIT Trial: Mirtazapine vs Ondansetron for HG

From Dr. Chapa’s OBGYN Clinical Pearls Dr. Chapa’s Clinical Pearls

Hyperemesis gravidarum (HG) represents the most severe end of the nausea and vomiting of pregnancy spectrum. It has a reported incidence of approximately 0.3–3% of pregnancies and is the most common cause of hospitalization in early pregnancy and the second most common cause of hospitalization in pregnancy overall. In June 2024, the ACOG published a Clinical Expert series summarizing the inpatient management of HG. In that guidance, it describes mirtazapine as an “alternative pharmacologic” option. How effective is this medication compared to ondansetron? A new study (published ahead of print on 12/30/25 and officially out June 2026), out of Denmark, sheds some new light on this medication. This trial is the first double-blind RCT comparing mirtazapine to ondansetron AND placebo. Although a BIG limitation of this study exists (which we will discuss), it does provide some interesting insights. Listen in for details.

1. (ACOG CES) Clark, Shannon M. MD; Zhang, Xue MD; Goncharov, Daphne Arena MD. Inpatient Management of Hyperemesis Gravidarum. Obstetrics & Gynecology 143(6):p 745-758, June 2024. | DOI: 10.1097/AOG.0000000000005518

2. Ostenfeld, AnneDroogh, Marjoes et al.Mirtazapine or ondansetron for hyperemesis gravidarum. A randomized placebo-controlled trial. American Journal of Obstetrics & Gynecology, June 2026