The Love Potion is a Hardmode thrown potion that functions similarly to Thrown Water, but inflicts no functional effect. Hitting a solid block will inflict all players, NPCs, enemies, and critters with the Lovestruckdebuff, causing them to emit red hearts for 30 seconds, similar to the Water Gun's dripping. This effect is purely cosmetic.
Despite the Princess Fish being available on the Nintendo 3DS version and having 'Material' listed in its tooltip, the Love Potion cannot be crafted due to a lack of Shiverthorn in the game.
It can be created and used in Pre-Hardmode worlds, if an artificial Hallowed sea or lake is created for fishing - or if either Princess Fish or the Love Potion itself is transferred to the world by a Hardmode player.
Since the Princess Fish (25) sells for more than the Love Potion (40), it is more economical to sell the fish than it is to sell the potions.
Lovestruck is considered a debuff because it cannot be terminated manually and the Nurse charges money for removing it, similar to other debuffs. Despite this, the debuff icon has a blue background, which usually indicates a buff.
This might be because the Love Potion is used to "make someone fall in love", which could imply that the target is unable to remove the effect.