I recommend a tongue cleaner.

This is a product I bought as a spare while using my current one. I bought it because they said it doesn't cause nausea, and while it doesn't completely eliminate it, it definitely makes it less nauseating compared to others. There are cheaper cleaners available, but I am satisfied with this one because it is hygienic to use. I recommend it to anyone who hasn't tried it yet. I noticed they sell it at Olive Young. It's good.