In The Amazing Spider-Man, Harry Osborn is suffering from an illness; is that in the comics? I (clearly) don’t read comics but I love watching Spider-Man movies. Thanks.
In the comics, Harry Osborne does not suffer from a terminal disease as he is depicted in The Amazing Spider-Man movies. He does, however, have a history of drug addiction, and mental illness, compounded by the fact that the Goblin Serum used to enhance himself also makes the user a bit more insane.
In the past, Harry has overdosed on LSD, and spent time in rehab and mental hospitals. Additionally, he has suffered amnesia, and had his mind merged (like when his conscious and subconsious were merged) and fractured again repeatedly over the years.