Player is inflicted with the Medicated status ailment for a duration of 15 minutes, preventing the use of other items that also give this status ailment.
Not exactly the best thing in the world, but I popped one right before my LS did Genbu, and it gave me 10 VIT. Meh, not bad, it's not like I spam meds during the battle either, so I guess that 10k wasn't a waste.
My MNK used this when soloing Dark Dragon for rank 3. I used this together with 1 Persiokos Au Lait and 4 X-Potions (and of course a Meat Chiefkabob). It was quite easy. Was down to 130 HP as lowest. But back to the subject of Vitality Potion. It gave me a +12 VIT that gradually decreased. Only lasted like 2 min or so. So you won't be able to use it like a big boost before all battles. But it sure helped me in this fight. The Dark Dragon just hit me for little over 20 HP/hit. And the Weaponskills barely got over 75 HP/each. So this should be used when really needed VIT. Like in BCNM-fights but not usable in normal XP-parties.
i heard that vit potion gives u 20 VIT not only twelve but ive never experienced it myself! looking to buy one but no one seems to make it and sell it in AH!