From Bulbapedia, the community-driven Pokémon encyclopedia.
Ginseng is an item in the Pokémon Mystery Dungeon series. It is a drink that boosts the power of the selected move, sometimes significantly. In PMD1, this effect works only for the team leader. However, in PMD2/3, Ginseng powers up the topmost move, making it possible to power up your teammates' moves as well. Ginseng's effect won't affect certain kinds of non-damaging moves. It also slightly fills the user's belly. It can be obtained by clearing team mazes and each of the type-based mazes in Makuhita Dojo in Red Rescue and Blue Rescue or as an occaisional reward in some rescues in Pokémon Mystery Dungeon: Explorers of Time, Explorers of Darkness and Explorers of Sky. Also, if you complete your first sentry duty in PMD2/3 with perfect results, one of the rewards is a Ginseng.
It can be sold for 600 Poké at the Kecleon Shop.
In Pokémon Mystery Dungeon: Explorers of Time, it can be found rarely on Mt. Mistral.