The swamp is said to gets its name from the rumored fever it harbors. The fever will make the victim get high temperatures before going insane and running into the swamp, to never leave again. The swamp is otherwise home to the isolated Swamp Hermit, a bog that acts like quicksand, and the titular Werewolf.
Fever Swamp has made a couple other appearances throughout the Goosebumps franchise. It appears in the video game Goosebumps HorrorLand as a water park area in HorrorLand, which hosts magic shows that are run by Horrifico and feature The Great Gargantua. Fever Swamp also appears as the center location in the fourth Goosebumps comic book arc, Secrets of the Swamp.