These potion side effect ideas are fantastic! My players discovered an NPC who operated out of a shop down a dark alley in town (kinda like that shady part of Diagon Alley, lol). This alchemist liked to "experiment" with potions, and many of the special potions had many of the effects listed here, and the fun was watching their faces when I explained the side effects. Watching the barbarian try and dex save to drink his special version of a healing potion was priceless. Is it wrong that my players now look wearily at any new magical item that they come across?