Coffee is generally considered to be safe. However, with some people (and some dosages), it can have serious side effects, such as heart problems, exacerbation of anxiety and bleeding disorders, and more. Oh, and it also makes some people poop! Learn more about the serious (and not-so-serious) side effects of drinking coffee due to a coffee habit, occasional caffeine consumption, caffeine withdrawal and more.Photo (c) Lindsey GoodwinDo you tweet? Follow About Coffee/Tea on Twitter.Are you on Facebook? "Like" About Coffee/Tea.