<p>Hookah use is a growing global health concern, particularly among young adults, with significant misconceptions about its safety. This study aimed to investigate the prevalence of hookah use and its association with knowledge of harmful substances and future susceptibility among university students in Iran. A cross-sectional study was conducted among 561 undergraduate students from Golestan University of Medical Sciences in Iran between April and June 2024. Data were collected using a questionnaire assessing demographics, hookah and cigarette use patterns, future susceptibility, and knowledge of harmful substances in hookah versus cigarettes. Statistical analyses included descriptive statistics, chi-square tests, and logistic regression. The lifetime prevalence of hookah use was 44.4%, with 16% reporting use in the past month. A significant portion of students (38.7%) were susceptible to future hookah use. Most participants demonstrated good knowledge regarding the harmful substances in hookah compared to cigarettes. However, knowledge of carbon monoxide and heavy metal content was associated with a lower risk of future hookah use susceptibility (AOR = 0.498 and AOR = 0.490, respectively). Prior hookah use (lifetime, past year, past month) was significantly associated with increased susceptibility to future use (<i>p</i> &lt; 0.0001). Hookah use is prevalent among Iranian university students, and prior use significantly predicts future susceptibility. While knowledge of hookah’s harmful effects is relatively high, it does not fully mitigate the risk of future use. Interventions should focus on addressing attitudes and social influences that promote hookah use, alongside enhancing knowledge about specific harmful components.</p>