Aside from water, you can also drink sports drinks, coco water and hydrating salts drinks. The drinks that you must be drinking should not contain a drop of sugar because sugar can dehydrate you some more. There are sports drinks that are sugarless and coco water is often sold without added preservatives. If water is getting boring, these drinks can also help with the hangover.
These drinks contain electrolytes. It will regulate the fluid components of your body because it contains sodium and potassium. In a time like this, you will need a refill on electrolytes.