AimTo identify the symptoms and relevant factors associated with acute adrenal insufficiency of early‐onset Sheehan syndrome.MethodsWe retrospectively reviewed the charts of 125 women admitted to our intensive care unit because of postpartum hemorrhage between January 2011 and December 2021. Three women developed acute adrenal insufficiency. We investigated the total blood loss, shock status, consciousness level upon arrival, and intensive care provided to the women. We also analyzed the symptoms and laboratory data that led to the diagnosis of acute adrenal insufficiency. Continuous variables were presented by median (minimum–maximum).ResultsThe medians and ranges of age, total blood loss, and shock index [heart rate/systolic blood pressure] on admission were 33.1 (17.2–45.3) years, 3351 (595–20 260) g, and 0.94 (0.55–2.94), respectively. Seven women were older than 40 years, 28 experienced >5000 g blood loss, 17 had shock index >1.5, 27 had impaired consciousness upon arrival, and 15 underwent hysterectomy. Women who developed acute adrenal insufficiency were <40 years old and had a bleeding volume of over 5000 g, impaired consciousness upon arrival, and had undergone hysterectomy. They had experienced lactation failure, presented with hyponatremia‐related symptoms on postpartum days 8–9, experienced general malaise, headache, and impaired consciousness, and showed severe hyponatremia.ConclusionsMassive postpartum hemorrhage over 5000 g, impaired consciousness upon arrival, and hysterectomy as a hemostatic measure were relevant factors associated with acute adrenal insufficiency of early‐onset Sheehan syndrome. Hyponatremia‐related symptoms occurring after lactation failure are indicative of the onset of acute adrenal insufficiency.