In hyperemesis gravidarum, which antiemetic should be withheld unless prescribed?

• A. Dicyclomine
• B. Promethazine
• C. Ondansetron (Zofran)
• D. Metoclopramide

Answer: (C)

In managing hyperemesis gravidarum, safety of antiemetics is key because some drugs carry risks to the fetus or to the mother's heart. Ondansetron is a potent antiemetic that has been associated with QT interval prolongation and, though data are mixed, concerns about fetal effects in early pregnancy. Because of these potential risks, it should be used only when prescribed and supervised by a clinician who can weigh benefits and risks for the individual patient.

Dicyclomine isn’t an antiemetic at all, and it’s an antispasmodic that can have anticholinergic effects—so it isn’t the appropriate antiemetic to rely on in this situation. Metoclopramide and promethazine are antiemetics that clinicians may use in pregnancy, with monitoring and clinical judgment. So the antiemetic that should be withheld unless prescribed, due to safety considerations, is ondansetron.