Remember that video I gave you a link to the other night? A man who was so ill that he would later die from his illness was neglected and mistreated by paramedics and a bunch of police officers.
They let him stumble and literally fall on his face rather than offer so much as a helping hand. All he wanted was to get to a hospital, but all they saw was somebody who was probably homeless and drunk or high. (He was neither, actually, but he looked like he was.)
They wouldn't take him seriously because because they evidently presumed he had caused his own problems by drinking or drugging.
But why should it matter even if he had been ill because he had taken something? If he really had been drunk or high, would his life not be worth saving? Shouldn't their response have been something more like: "Oh my gosh, I think he's overdosed. Let's rush him to the hospital as fast as we can!"
That's the genre of stigma I think you're writing about.
It's the kind of stigma that caused those medics and cops to behave as if that man didn't deserve their help.