Background: Data regarding prevalence, characteristics, and factors associated with caffeine-withdrawal headache are lacking. This work aimed to study the prevalence of caffeine-withdrawal headache among caffeine consumers during Ramadan's first day and describe its characteristics and associated factors. Methods:This analytical cross-sectional study targeted 755 caffeine consumers eligible to fast on the first day of Ramadan. Two methodological approaches were followed: an online open survey and a face-to-face interview. Using an adjusted form of food frequency questionnaire, eligible participants were requested to report their intake of caffeine-containing products during the last week of Shaaban month, the month preceding Ramadan. Results:The prevalence of caffeine-withdrawal headache on the first day of Ramadan was 419 (55.5%), with 95% confidence interval (CI; 51.9-59.0%). The headache in the majority of the participants was throbbing in character (249/419, 59.4%), diffuse (146/419, 34.8%), and moderate in intensity (227/419, 54.2%). Participants who developed caffeine-withdrawal headache had significantly higher body mass index (27.2 ± 5.1 vs. 26.3 ± 5 [mean ± standard deviation], p-value = 0.012), daily caffeine intake, mg (316 [185.2-537.8] vs. 144.4 [60.0-312.4] [median interquartile range (IQR)], p-value < 0.001), and caffeine intake mg/kg body weight (4.7 [2.6-7.2] vs. 1.9 [0.8-4.4] [median (IQR)], p-value < 0.001) than participants who did not develop it. Mild, moderate, and severe caffeine use disorder were found to have adjusted associations with developing caffeine-withdrawal headache. They increased the odds of headache by 5.3 (95% CI = 3.40-8.3), 10.2 (95% CI = 5.9-17.5), and 15.5 (95% CI = 9.0-26.8) times, respectively. The optimal cut-off value of daily caffeine intake/Kg body weight was determined at 1.97 mg/kg with an area under the curve of 0.722 and sensitivity and specificity of 85.1% and 50.2%, respectively. Conclusion:Daily caffeine intake/kg body weight and caffeine use disorder are significantly associated with a caffeine-withdrawal headache.