No

oh ik this one basically phineus and ferb were shot by doof's fusion inator or something

Phineas and Ferb conducted a expirement in Gomel and would later get severe pain, but after weeks it would wear off, fortunately nobody seems to notice so they go to Isabella to show themselves but she sees a horrific site between interacting with them.

She wanted to try out Ferbs new made “experimental drug”
She died the next hour.