Final answer:
The potential drawback of creatine monohydrate supplementation is water retention and weight gain.
Step-by-step explanation:
The potential drawback of creatine monohydrate supplementation is that it may result in water retention and weight gain. Creatine increases cell volumization by drawing water into muscle cells, which can make them larger. This intracellular retention should not be confused with the common myth that creatine causes bloating, which is intercellular water retention.