Most human medications are very toxic to dogs and cats. There are a few exceptions like Benadryl. But, you shouldn't give your pets any human medication without first consulting a vet. We have given our dog Benadryl before when he had a stuffy nose, but we were told by a vet that is was ok. I also gave my guinea pig children's cold medicine when he had an upper respiratory infection, and it worked quite well. I believe Pepto Bismol is ok too, but I'm not sure about that. But, most medications are bad, and you should ask a vet before giving your pet anything.
As for food, there is a pretty long list of dangerous foods for dogs. I know about onions, raisins and grapes, macadamia nuts, chocolate, and a few others. The thing about raisins and grapes is, it does not hurt all dogs. I've actually had dogs who ate grapes with no problem. You would think that all dog owners know not to give their dog chocolate. Ever since I was a young child, I knew that chocolate was bad for dogs. But, there are some people who will give their dog an after dinner chocolate or hot chocolate every day. I use to watch "it's me or the dog" all the time. The dog trainer "Victoria Stilwell" had to tell several people about how chocolate was dangerous for dogs. I always thought it was common knowledge, but it surprised me to see so many people giving their dog chocolate. That was a good post. People need to be informed about stuff like this.