My wife struggled with this too. If truth be told, nothing really worked. Mornings were especially bad. Add to that, the taste of water made her gag too for some reason.

She tried everything that was given to her. Mouthwashes, sprays, pills etc etc.

You have probably been told this, but do stay away from any mouthwashes that contain alcohol as they dry your mouth out at the best of times.

She also use mint free toothpaste (Oranurse) as she found mint exasperated the issue and hurt her mouth. Oranurse is made for people on chemo, who have altered taste and can't stand mint.