Andrew Wyatt’s review published on Letterboxd :
The Cleanse is an odd beast indeed, a comic riff on The Brood (1979) that feels like something Joe Dante or Robert Zemeckis might have helmed in the mid-1980s. Even that formulation gives the film too much credit, though – director Bobby Miller lacks the wit and journeyman talent of those filmmakers. The Cleanse isn’t remotely frightening or freaky enough to be a body-horror feature (the gross-out stuff is strictly PG-13), but it’s remarkably laugh-free for a comedy. So, what is the viewer left with? Johnny Galecki makes no impression at all in the role of a sad sack who attends a strange New Age purification retreat. At least the practical effects are striking when he and his fellow seekers start vomiting up creatures that embody their negative impulses. Although it aims for a bizarrely melancholy vibe, The Cleanse is ultimately just lifeless and uninvolving, distinguished only by its faintly gnarly premise and its ugly-cute creature designs.