- "Hello... and you are...? Say, have you ever suffered from some type of sickness or condition that you couldn't get cured at a hospital? For example, being "Diamondized," where your head gets as hard as a diamond... Or... "Mushroomized," where you have a mushroom on your head... If you're ever stuck with these types of embarrassing conditions, we of the magic healing shrine are here to ease your pain. We're ready and waiting... in the lobby of hospitals all over the world. The person next to me is the great teacher of magic healing."
- — Healer's assistant (EarthBound)
Mushroomization is a status condition caused by mushroom enemies such as the Ramblin' Evil Mushroom. In the overworld, the mushrooms cause the controls to scramble positions while walking around and it also makes a mushroom appear on the head of whoever is inflicted. While in-battle, it may cause a character to attack a party member or heal an enemy. If the prompt "[character name] is feeling funky!" appears after you select your move, the effects will take place. Sometimes when an inflicted party member attacks a PSI using enemy, the enemy will get mushroomized. One way to remove the mushrooms is to go to any hospital and pay $50 for each inflicted party member. There is also a man in the hospital who will buy the mushroom off your head for $50. There is also a girl foraging for mushrooms in Peaceful Rest Valley who will offer the same service as well as the same price for the mushrooms. In addition, the hot springs in Saturn Valley can also remove the mushrooms. PSI abilities cannot remove mushrooms.
In Mother 3
The Mushroom effect in Mother 3 is inflicted upon the party members by mushroom-based enemies such as the Ramblin' Mushroom. They have the same effect as EarthBound's version of the status effect, although no mushrooms can be seen on their head. This effect ends after a certain amount of time.
There is also another type of "mushroomization" in Mother 3 that does not appear in the other two games. On Tanetane Island, Lucas and co. eat some Hallucination Mushrooms which cause the party to, as their name implies, hallucinate insanely despite them fully healing the party. This is vital to the story and is unavoidable; again, PSI abilities cannot affect this. This effect ends when Mixolydia smacks the party over the head with a paper fan.