The aim was to evaluate if the addition of video discharge instructions (VDIs) to usual verbal information improved the comprehension of information provided to caregivers of patients who consult for acute gastroenteritis (AGE). We conducted an open-label, parallel, randomized trial, enrolling patients who consulted for AGE at a tertiary hospital. First, caregivers answered a written test concerning AGE characteristics and management. They were randomly allocated to a control group, which received the usual verbal instructions, or to an intervention group, which additionally received VDI. After discharge, caregivers were contacted by telephone and answered the same test, satisfaction questions, and follow-up information. From September 2019 to March 2020, 139 patients were randomized, 118 completed follow-up. The mean score was 3.13 (SD 1.07) over 5 points in the initial test and 3.96 (SD 0.96) in the follow-up test. Patients in the intervention group had a greater improvement (1.17 points, SD 1.11) than those in the control group (0.47 points, SD 0.94, p < 0.001). In the follow-up test, 49.1% in the intervention group and 18.6% in the control group answered all questions correctly (p < 0.001). There were no significant differences in return visits. Caregivers gave high satisfaction scores regardless of the allocation group. Conclusion: Video instructions improve caregivers' understanding of discharge information. Trial registration: [NCT04463355, retrospectively registered July 9, 2020]. What is Known: • Poor comprehension of discharge instructions leads to incorrect treatment after discharge, increased readmissions and a reduction of caregivers' satisfaction. • Video discharge instructions are useful providing concise information independently of the patients' health literacy level or communication skills of the health care provider What is New: • The addition of video discharge instructions to verbal instructions improves caregivers' knowledge about AGE improved with respect to those who only receive verbal instructions • Video instructions do not add extra time to the emergency department visits