| "All godchildren look the same."
This article is about the illness that effects fairies. For the "Oh Yeah! Cartoons" short, see The Fairy Flu.
The Fairy Flu is an illness that affects mainly fairies, causing them to temporarily lose control of their magical powers.
When the fairy sneezes, it alters reality in various ways. For example, Timmy asked Cosmo and Wanda what the fairy flu was, Cosmo told him it was a disease that affects Fairies and then he sneezes and magically poofs Timmy's House to the Moon. These sneezes can also affect things away from Cosmo and Wanda. They both started sneezing at the same time, causing Tootie's head to change into various sharp objects and dangerous tools while she ran around chasing Timmy trying to kiss him.
It is shown in "One Flu Over the Crocker's Nest" that humans can catch the Fairy Flu as well, which can give them "temporary magical powers". This can cause the victim to unknowingly grant themselves wishes while they have the illness.
According to "The Fairy Flu!", Making the fairies eat a large amount of sauerkraut will cure them of this ailment. There was plenty of sauerkraut being served at Tootie's birthday, so Timmy enlists her help stuffing Cosmo and Wanda, who were disguised as balloons, with sauerkraut. When Tootie asked why, Timmy explained they were "rare German balloons". Cosmo and Wanda were quickly cured and were able to use their magic to revert the dangerous changes their illness had caused, mainly a rampaging dragon Vicky destroying the party.
However, One Flu Over the Crocker's Nest (The Flu's only main series appearance) does not make any mention of this.