Mom has rhinitis and will not use her fluticasone. At the table, she will wipe her nose with one thin tissue? Then stick her finger up her nose with the already wet tissue. It is quite nauseating for some at the table. I don't know how to ask her to stop or encourage better etiquette because I don't want to embarrass her. At every meal, she leaves a pile of wet tissues at the table.
Who are the other people at the table? Family, I assume? They can probably be more easily taught to avoid looking at your mom's unsavory behavior than she can be taught to change. Yes, this would be disgusting to watch. So, don't watch.
Bless you for not wanting to embarrass her. That is very kind. And it is kind, also, to be concerned for the feelings of the rest of the household. But caring for a person with dementia presents these kinds of challenges. There is some inevitable unpleasantness.
Perhaps it would be an option for Mom to have her meals separately, in a pleasant location. Maybe you could sit with her and chat, without necessarily watching her, and then have your meal with the rest of the family. I imagine, though, that her behavior is similar when she is away from the table, and I certainly don't encourage isolating her from the rest of the household all of the time.
It would be interesting to hear how you ultimately resolve this. We learn from each other!
I regret it now, but I went through phases of trying to police this by nabbing each tissue off her, dropping it in the bin, and replacing it with a clean one from a box on the table. For one thing we got through a heck of a lot of tissues; for another I once overheard my sister referring to me as "the Tissue Nazi"; and for another my mother never got used to having her Kleenex whisked away.
I'd have saved myself a lot of stress by looking the other way and remembering that they were her germs, already in her body.
You could pop a little plastic canister by your mother for her to put the wet used ones in, maybe? Oh dear! I do feel for you.
With the dementia, embarrassment isn't the way you normally think of it, imo. You can't keep the same sensibilities that you would have with someone who does not have cognitive decline. Your mom isn't likely to see your intervention on this the same way she would if she didn't have dementia, so the embarrassment concern would not be a factor for me. You just have to take care and control of the situation.
If the fluticasone would help her condition, then I would ensure that she's using it. Sometimes, the patient's ability to process and remember why they need something is lost. I'd just administer that medication at a regular time each day, according to her prescription. If she's resistant, I'd deal with that, so that she gets her meds.
And, I would remove tissues from the dining table and her hands, so she doesn't have the option to use them during the meal. If she insist that she needs to blow, I'd say mom, we have to leave the table to blow our nose and escort her out to do it.
Due to the brain damage, teaching her how to do it differently, isn't really an option that I am aware of.