Blain LaMotta’s review published on Letterboxd:
Drugs are destroyers of all that is sensible. They expose weakness and infect everything you hold dear. That doesn't mean they can't be a learning experience however, especially if they can inspire cinema this raw and electrifying. The path toward understanding can eventually lead to change, but you have to get your hands dirty first. Heaven Knows What is such an increasingly grimy experience, that it is hard to shake or even accept at first. It blurs the lines between reality and fiction with such acute precision, that you feel as though you lived it. Arielle Holmes, in a performance of astonishing emotional complexity, draws from her own personal hell in order to evoke the authentic feeling of being trapped by that which you love. When you are trapped, you are stripped of all control. It is that sensation of helplessness that the Safdies evoke with compassion and shocking gravity. The restrictive camerawork, probing synth, and seedy milieu of New York City helps compound that atmosphere to the point of suffocation. The relief is that we can escape at any point relatively unscathed. Others are not so lucky.