Cat/dog reactions to different medicines?

Kind of an odd question but here goes. I’m just wondering if Cats and Dogs are affected by certain common human medicines and if they are affected negatively or positively. I did a few google searches and searches on a few cat/dog advice sites but nothing like what I was looking for.

I’m asking partially to find out if they get into something do i need to run them to the hospital , and also asking if any simple household medicines can be used to treat common symptoms in cats/dogs.

Things like tylenol, opiate painkillers(mainly are they very dangerous, my mom often drops pills behind couches and on the floor and doesnt find them),. cough medicine,pepto, etc. I’ve heard some people give their dogs/cats baby tylenol for arthritis and other similar pain problems but is that really healthy? Basically any common meds that one might have in a household.

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