Not only does this medication leave a bad taste in your mouth, but it can also hinder your sense of taste altogether. Prednisone is a drug used to treat cancer and has had several complaints of causing oral thrush. Oral thrush, which is basically a yeast infection, can cause your tongue to feel furry, sore, and white in colour. It can also cause you to lose your sense of taste and causes cracks around the mouth. As if cancer patients didn’t have enough to worry about.