What’s wrong with Lovecraft? ;p
Well, it isn’t that magic is real, the Gods are real and interact with the people. The magic you refer to is the ‘death magic’ or summoning a demon from the Bastard to kill your enemy, and in return you are also hauled off dead. It is in the not being successful that the temple inquisitors want to have a bit of a word with you. Though in The Hallowed Hunt, the wildings had a tradition of shamanisn and ‘possession’ of an animal ‘soul’ that the followers of the Five Gods persecuted.
So effectively in both cases, it wasn’t the magic itself that was dangerous, in both cases it was the established religionists who were the danger to the one practicing. [unless you consider the fact that to successfully curse someone meant you also were going to be hauled down to ‘hell’ by the summoned demon. The act of summoning the demon for revenge was not taken lightly, it was tee ultimate act of desperation.]
In Diskworld 7a can get you in real trouble.
In the Mordant’s Need series, magic works through mirrors and if you look at your own reflection, even if you’re not a mage, you go insane.
In another magic system in a story I read somewhere, probably in Dragon magazine, to create a magic item, you had to use the soul of a mage, perforce killing them. The more powerful the mage, the more powerful the item. Therefore while being a mage was certainly useful, it made you a target, and being a powerful mage made you a very big target. In the story I read, the protagonist mage had been brought up with the specific intent of killing her.
Hart’s Hope, by Orson Scott Card. I haven’t read it, but I’ve read an essay he wrote about it, and there’s a whole lotta human sacrifice going on for magic to work.
In Ben Aaronovitch’s River of London series, using too much magic will kill a person; no one knows how much is too much, though the main characters are trying to figure it out in between cases.
In Larry Niven’s short story “Convergent Series” (contained in the collection titled, oddly enough, Convergent Series), summoning a demon is a really bad idea. The grimoire that tells you how to summon it does not tell you about the fine print. (They have power over documents that mention their names.) You get one wish, then the demon takes you to Hell.
As with the 5 Gods universe, getting revenge on someone might make going to damnation worth it. I would be willing to bet that there were a fair number of people in various concentration camps that would happily have summoned up a demon and cheerfully gone to damnation to have ultimate revenge.
Stephen King’s Firestarter has several people with telekinesis, which is shown to cause nosebleeds and, ultimately, brain damage. Not strictly magic in context, but close enough.
Obligatory TV Tropes link: Blessed With Suck.
Black Easter by James Blish.
Possibly the most ‘realistic’ book with magic use in it, ever.
In Charles Stross’s Laundry series, the magic is very dangerous to the user and to life on earth since you can never be sure what Lovecraftian horror you might summon.
In both Laura Anne Gilman’s Wren and related series, as well as in the Vineart novels, magicians must undergo serious apprenticeships to avoid being dangerous to themselves and others. Same thing in Benedict Jacka’s stories.
Then there is the sorcery in Brust’s 500 Years After that ends in holocaust that kills most of the participants from the injudicious use of “elder magic”. But mostly Brust’s sorcery is mundane and safe. But not all.