The aim of this study was to understand better the pathophysiology of this intoxication by evaluating the effect of mad honey ingestion on Inferior Vena Cava (IVC) diameters and IVC Collapsibility Index (IVC-CI) and develop an objective algorithm for the duration of fluid replacement and observation. The patients with the medical history of mad honey ingestion and admitted to the emergency service due to the signs of mad honey poisoning were analysed. Their data concerning age, gender, admission symptoms and the time of onset of these symptoms, the vital signs during admission, the administered treatment, the post-treatment recovery time and vital signs were all recorded. The inferior vena cava diameter and the IVC collapsibility index were assessed by ultrasonography. Of 29 patients included in the study, 79.31% were male, the average age was 52.76 +/- 17.52 years, and the most common cause of admission was dizziness. While 0.9% saline solution was administered to all patients, in 82.75% intravenous atropine was started. Significant differences were determined between the vital signs, the inferior vena cava diameters, and the collapsibility indexes of the pre and post treatment periods. The ingestion of mad honey should be questioned in the medical history in patients who were admitted to the emergency services due to hypotension, bradycardia, and syncope. The assessment of the vital signs and the measurement of the inferior vena cava diameters of the patients should be the parts of the follow-up. The monitoring of the responses to the administered atropine and/or normal saline solutions should be made by the ultrasonographic assessment of the inferior vena cava diameter and the IVC Collapsibility Index (IVC-CI), in addition to monitoring the vital signs.