With all the diseases and the poor hygiene of the old times, the pharmacies were really useful. So there were at least one of them in the big cities of my country . I bought the shelves and the clutter to decorate the shop. Then I downloaded the ***usable*** potions come with several effects when a sim drinks them.
links to create your own.
Clutter and shelves
http://www.medievalsims.com/forums/viewtopic.php?f=171&t=4012
http://www.parsimonious.org/furniture2/pages/k8-Oggs_N_Ends.html
http://feydecay.tumblr.com/post/65437006649/the-lovely-lama-has-done-it-again-an-amazing-set
http://zeussims.livejournal.com/7702.html
potions
http://modthesims.info/d/188471
http://modthesims.info/download.php?t=211622 (really useful with all this death around)