Mudslide Cocktail

How long will a mix of cocktails if it says refrigerate after opening?
I have a bottle of Mudslide mix daily including non-alcoholic type, and my sister put it on the counter the other night after mixing for us. I noticed the bottle until the next morning and it said to refrigerate after opening. How long is too long to let something like this? In the case of milk or something like that would pull me away, but could this be so harmful?
If there is a warning on the bottle, it's there for a reason. I have no idea what the ingredients, but is likely to soured during the night if it's hot there.
Mud Slide Cocktail Drink Recipe