¹Department of Pharmaceutical Technology, Faculty of Pharmacy, İstanbul University, Beyazıt 34116, Turkey DOI : 10.29228/jrp.471 There are various ways to deliver drugs and each one has its ups and downs depending on the purpose of use and the patients themselves. And among these drug delivery systems, the intranasal path stands out as one of the more exciting and challenging ones. Despite being perhaps the most commonly used path of delivery, the oral route is subject to facing various roadblocks in terms of efficacy and bioavailability, requiring a certain amount of dosage and synergy from the active pharmaceutical ingredient that is being used to be effective. When said active pharmaceutical ingredient is ineffective via the oral route, has to be given in small doses, or has to enter circulation quickly to manifest its effects, it inevitably falls out of favor. In its place, the intranasal route can act as a viable substitute. Although there are several methods to formulate intranasal drugs, naturally, the intranasal route possesses advantages and disadvantages of its own. Thus, in situ gel systems have emerged as a favorable preference among these formulation methods. Possessing the upsides of not only gels but solutions as well, the in situ gel systems effectively address and solve some of the disadvantages posed by intranasal drug delivery systems. This review article aims to provide a general understanding of intranasal drug delivery systems and in situ gels, both separately and together as a combination, while underlining the importance of each and also providing examples from existing literature to display their range of applications. Keywords : Drug delivery system; in situ gel; intranasal; nasal; pharmaceutical; polymer