Rather than leave a slow-draining toilet alone, work to remove the stoppage before the toilet clogs up completely. You do not need to use any liquid solutions to free the clog, especially since many of those solutions are dangerous to use in a toilet. With solid instruments you can free the clog in a matter of minutes, restoring the toilet's draining capabilities to normal and avoiding a complete clog of the toilet's drain in the near future.
Spread petroleum jelly on the rim of the rubber cup on a toilet plunger. This helps apply more pressure to the toilet's drain pipe.
Place the plunger's cup so that is completely covers the drain hole in the toilet bowl. Firmly push the plunger's handle down, and then pull it up while keeping the cup in place over the drain hole. Repeat this action at least a dozen times. Remove the plunger and try flushing the toilet again.
Insert the flexible end of a toilet auger into the bowl, making sure the bent portion of the end of the auger is pointing upward. Turn the crank on the auger clockwise to feed it into the toilet's drain.
Stop turning the crank once you have unwound the entire flexible portion of the auger. Turn the crank on the auger counterclockwise as you pull up until the auger winds up completely.
Flush the toilet to make sure it drains normally. If not, feed the auger back into the toilet's drain pipe twice more, once on the right side and once on the left side.