Poison Mushroom

The Poison Mushroom is a harmful Mushroom that hurts the player. It first appears in Super Mario Bros.: The Lost Levels, which was initially a Japan-exclusive game. It has also become an item in the Mario Kart series. Its main purpose is to slow down other players, though it originally shrank them.

The Poison Mushroom started out as a CPU-exclusive item that only Peach and Toad could use, but ever since its return in Mario Kart Insanity, players could now use it.

Mario Kart DS Redux (2021)
The Poison Mushroom appears in Mario Kart DS Redux, a remake of Mario Kart DS. In this game, it can be obtained in the top six positions (1st to 6th place). Like in Super Mario Kart, the Poison Mushroom shrinks the player who collides with it and grows an already shrunken player back to normal size. Unlike the aforementioned game, however, players can now use it, and it also reverts Mega Mushroom racers to normal size. It also unflattens the user if they're flattened and acts like a Red Shell, targeting the nearest kart ahead of the user.

Appearance
The Poison Mushroom has a different appearance, depending on which game it appears in. It is usually depicted as a purple mushroom with either magenta or pink spots. However, it may have green spots instead. In some games, it has a blue cap and green spots, looks similar to a Mushroom or Super Mushroom but with angry eyes, or has a black cap with magenta spots. It may also have a brown cap with black spots, and indigo cap with a blue skull, or a blue cap with a white skull.

Mario Kart DS Redux
"The Poison Mushroom makes its return from Super Mario Kart, and this time, it's an item that everyone can use. Like the Banana, this item can be used to block incoming items, and running into it will shrink you. If you're already shrunk, it will return you to normal size."

Trivia

 * The Poison Mushroom has been absent from seven Mario Kart games, spanning a 27 year absence from Super Mario Kart (1992) to Mario Kart Insanity (2019).