It was made in 2000 by Darren Aronofsky who's also directed The Wrestler. He clearly wants to show images that Hollywood movies would typically cut away from. He's not afraid to try something new in order to gain a reaction out of an audience that you can never normally grasp from a film.
In case you were wondering what the storyline involves, here's the few elements that really are shocking - A mother addicted to diet pills, a heroine addict, twisted sex scenes and some frankly grotesque images of the effects that drugs cause. If there's ever a reason not to take drugs, then this film provides that. Just show it to kids in the awareness campaign, they certainly will never want to talk about them again, let alone take them.
It's not a film that's preaching to you not to do these things, it's a film designed to open up your mind to the nitty gritty underworld that is often glamorised in cinema today. Even though Jared Leto and Jennifer Connelly are very gorgeous faces to have on the screen, they soon become a little less like eye candy, and more... Eye terror. We see their deterioration in a way that makes you connect with them; not necessarily a sense of sympathy, but more a feeling of helplessness towards them. And Marlon Wayans can actually act seriously! He offers a more sensible character (using the term loosely) by pointing out the effect that this life is having on their lives.
The editing in the film is also purely created to make you feel as tense as possible. It contains multiple collages of clips from pupils widening, injecting drugs to clips of a mother being electrocuted... It's not for the faint hearted. But it's a necessity to see this film if you're a film fan. It creates cinematography in a way that really inspires you to make a film. It's seems too real, you become wrapped in this world for the hour and a half, and once you're out of it you still find yourself flashing back to scenes in the film. It's mesmerising to watch.
So overall, as long as you prepare yourself to watch something that's going to shock you to your very core you will be fine... I hope. You MUST see this film. It's a cult and a good one at that.