An oral solution and a syrup are both types of oral liquid medicines, but the terms describe different aspects of the formulation. An oral solution is a liquid formulation in which the active pharmaceutical ingredient (API) is completely dissolved in a suitable liquid vehicle, resulting in a clear and uniform preparation. A syrup, on the other hand, generally refers to a sweet and viscous oral preparation, often containing a high proportion of sucrose or another suitable sweetening agent. A medicinal syrup can also be an oral solution when its active ingredient is fully dissolved. The main difference is therefore not simply that one is a solution and the other is a separate type of liquid medicine. Oral solution describes the physical state of the active ingredient, while syrup commonly describes the nature of the vehicle, particularly its sweetness and viscosity. Depending on its composition, a syrup may meet the characteristics of an oral solution. During development, factors such as solubility, stability, taste, viscosity, microbial quality, packaging, and dose delivery need to be considered to ensure the final oral formulation is suitable for its intended use.