Anhydrous oral care compositions and methods for preventing phase separation in the anhydrous oral care composition are disclosed. The oral care composition may include an orally acceptable vehicle, a thickening system, and a whitening agent. The orally acceptable vehicle may include propylene glycol, and the thickening system may include a polymeric thickener. The polymeric thickener may be or include a copolymer of 2-acrylamidomethylpropanesulphonic acid or a salt thereof.