I like lying in my bed with my arms up, but my cat sometimes comes to lick my armpits. His sandpaper tongue doesn't feel that nice. I'm using a stick antiperspirant, but he usually does this in the evening after the antiperspirant is long absorbed.
What is so tasty about my stinky, sweaty armpits? Is it healthy for my cat?
Humans secrete a fair amount of salt when sweating and many animals, especially cats, are attracted to the taste of that for some reason.
Another reason is, actually, scent. Your cat may be trying to apply their scent to you in, well, a fairly obvious spot for them to override.
A third reason is grooming. Cats will groom their human companions. This is a sign that they're quite relaxed and comfortable around you.
As for health, well I can't say, except that I doubt it's dangerous if the antiperspirant is truly gone. You could look at citrus-based deodorants as a deterrent since your cat won't like the taste. Might sting a bit though...
