A plunger will be the most effective way to unclog a toilet. Although a toilet bowl brush is not an adequate substitute, you can always try it if you are desperate. To do this, wrap the toilet brush with a plastic bag and secure it with a rubber band. Then, put the brush in the toilet and apply a rhythmic pressure similarly to how you would use a plunger. If this does not break up the clog, there are a couple other options that you can try to unclog a toilet without a plunger. For example, you can add dish soap to the toilet bowl, as sometimes that will loosen up the clog.