The Borgified Corpse wrote:
I've only seen "The Mind of Evil" once and I don't really remember that part. What happened?
There;'s a scene while the prison is under the control of the prisoners/the Msster, and the Doctor's comatose after being attacked by the Keller Machine, where Dr Summers (the ubiquitous Michael Sheard) gets to examine the Doctor very briefly, and gives Jo something to help the Doctor recover when he's awake enough to take it.
When the Doctor does come round, he looks at it and rejects it, saying "It would have killed me." It's a nice throwaway to the Doctor looking human, but that he isn't.
At some point, someone saw that scene, assumed the drug was aspirin, mentioned it in a fanzine, so it became a given that aspirin killed Time Lords for years...