Potion of Diminution

When you drink this potion, you gain the "reduce" effect of the _enlarge/reduce_ spell for 1d4 hours (no concentration required). The red in the potion's liquid continuously contracts to a tiny bead and then expands to color the clear liquid around it. Shaking the bottle fails to interrupt this process.

Source: 5e Core Rules · OGL-1.0a · 5.1