A-ha! Got this. Searched my old Total Film mags for the answer, well, at least one possible solution. For the movie BLOW, Johhny Depp, Penelope Cruz et al had to hoover up baby laxative. Ssssnffff! According to director Johnathan Demme, it “stufffs you up and makes you want to puke, so we tried not to do too many takes. We’d do one or two then give Johnny loads os tissues to clear his head”. QED, methinks.