This achievement will come naturally over time as you progress through the game, but if you want to knock it out quickly you can do so pretty early on.
SAVE YOUR GAME. This way you can load it back up after popping the achievement and keep al your potions.
Once you get to the island of Teer Fradee you should have a good amount of potions in your inventory already. Hit
and scroll over to Potions. Press
on the first potion to drink and then continue to spam
until you have drank everything in your inventory.
Next, head to the merchant in the Copper District. Sell everything in your inventory to the merchant and then buy all the health potions and magic potions you can from him. I think he had 8 each in my game. If you have any gold left over, buy as much of the cheapest potion available that you can. Now spam drink everything you just bought and it should be enough to hit the 50 mark and pop your achievement.
Now you can reload your save and continue on as normal.