Is Milk of the Poppy real?

In Game of Thrones, Milk of the Poppy is used as an anaesthetic, commonly to induce sleep in order to treat head trauma and/or extreme pain. In real life, Milk of the Poppy with he inducing effects that it has in the show and books isn’t inclusively ‘real’, but there is Poppy Milk, which is taken from the exact same method. read more

Overuse of milk of the poppy may make the user's face become puffy. In Meereen, some pit fighters dull their nerves with milk of the poppy before going out to die in the fighting pits. Victors will drink milk of the poppy afterwards for the pain of their wounds. read more

In short, Milk of the poppy is opium, a complex mixture of opiates, mainly morphine and codeine, plus papaverine and dozens of other compounds with various effects. I'm wondering if the lack of addiction relates to the maesters' control of it. read more