"Ah, Kali beat me right there. I believe this is the one which is refered to as a potion which shrink things in size, to a "miniature version of itself" and should literally "shrink" somebody. Therefore it might also be used in items, by bathing the object, or just be used in living being, again, but with the same methodology. I doubt you need drinking to make it work... unless you want to shrink something inside your body, which is not such a good idea."

"There's a second possibility and that is: it only work on non-living beings, in which case, if splashed by this you would get your clothes shrink in size but you stay the same, though somewhat suffocatted^^"

*raise hand*

"Professor, what does 'Medicamentum Contraho' means? I'm pretty sure the first it 'Medication' so that makes me wonder it this isn't an antidote for another potion and/or spell. The second seem to say 'Contraction', which in a way is 'shrink in size'. I am curious to what it could be."