Mix creatine into a liquid right before consuming it, because it degrades rapidly in solution, especially if the liquid is hot or acidic.

noli's read

The idea that creatine degrades instantly in water is a common misunderstanding regarding the molecule's stability. Although creatine can indeed convert into creatinine (an inactive byproduct) under conditions of very acidic pH and prolonged heat, this process is relatively slow at room temperature. Research published in the 'Journal of the International Society of Sports Nutrition' indicates that creatine monohydrate is very stable in water for several days, or even weeks, if kept cool. The requirement to consume the mixture immediately is therefore an excessive precaution rather than a biological necessity for efficacy. There is no evidence suggesting a significant loss of benefits if the drink is prepared a few hours in advance. The advice is therefore an unnecessary optimization that adds a practical constraint without a solid scientific basis.

the sources

1. 1strongerbyscience.com