Why does my cat like licking my armpits?
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...
I can confirm the grooming - armpits are not the only... "interesting" place a cat will try to groom! My oldest cat likes to engage in quasi mutual grooming with me - she'll lick my fingers then rub herself against them. And my nose.
I know a cat who enthusiastically licks the soft skin at the inside of humans' elbows. I don't know whether she thinks she's grooming us, "nursing", some combination of the two or something else, but we've learned to deal with the scratchy tongue and she has learned to be more gentle...
One of my cats loved to shove her nose into my armpit. I always presumed that it was like the reaction to shoes -- some aromatic compound that she found appealing, or wanting to pick up my scent, or wanting to make sure I carried hers. I'm sure it would make more sense if humans weren't relatively nose-blind ... and if modern society wasn't so busy insisting that we suppress our scent.