My mom has Alzheimer's and dementia. For her safety, can I secure her bedroom door while I shower? Thank you.

That is super concerning,you should be able to take 15-20 minutes without needing to help her. You should get more help. Good Luck

I may be more concerned for you. If the needs are so constant that you can’t feel safe in a 20 minute break, it’s a big sign you need more help. What would happen to mom if you had an accident or became sudden unavailable? I hope you’ll make a plan for more help

my Mom 82 Ana has dementia I done ng it by my self caring for her I plan on buying a baby It’s like a TV and then it comes with the thing you can hear them crying or whatever because my mom is walking without her walker to sneak into the bathroom I can’t even have a nap so I know the feeling I’m scared that she might open up the door and takeoff in a condo

Does she get into that much trouble while you take a 15-20 minute shower, that it's necessary to lock her in her bedroom? Really?
How about hiring someone to come stay with her(with her money not yours) for a few hours to keep her occupied so you can do whatever you would like? Or you can even take her to an Adult Day Care Center up to 5 days a week, so she can be kept occupied and fed, and you can take as many showers as you'd like, or whatever else you might want to do.
It sounds like you may have bitten off more than you can chew right now, and it may be time to be looking into placing mom in the appropriate facility. And that's ok. A lot of folks come to the point where keeping their loved one at home just isn't working for them or their loved one anymore.
I wish you the best.

Simple answer – yes you can. Of course, for a short while, in her best interests, and think again if it prompts a major meltdown. Give her something to occupy her, and go take your shower.

How many young mothers lock their toddlers out of the toilet while they change a tampon, with screams and thumps on the other side of the door? I certainly did! No-one suffers long term.

I am thinking if you cannot take your eyes off her long enough to take a shower you must be exhausted!

What's making Mom unsafe alone? Does she walk unsafely, start cooking unsafely or wander outside?

Or does Mom 'shadow' you everywhere & you need some privacy?

When I had very young children - very different I know, hear me out.. child 1 needed constant visual attention. I had to bring her into the bathroom with me.

Child 2 was happy alone but an escape artist. A playpen only worked for such a short time.

I came to the realisation I could not it do it alone. I needed a support person.

I would have to shower when DH was home.

I imagine there will be mixed responses on whether locking Mom's door is ok or not - regarding her safety, fear, rights etc.

I think this is a good question to ask. It may start many more questions about your situation. How are you coping? Are you trying to do it alone? How much other family help have you got, or can get? What non-family services have you researched & considered?