I have been receiving Remicade infusions every nine weeks since 1999 (I believe or 2000). Matter of fact I am going tomorrow! I have not had a flare since then. In 2005, I was diagnosed with Anal Cancer, and noone can tell me if it was related to Crohn's or an effect from the Remicade. With Crohn's disease you are more at risk for developing some kind of GI tract cancer, and with the Remicade it has been noted that some were diagnosed with Lymphoma. So who knows.
Everyone is different and some can tolerate Remicade with no side effects and some, like myself, get the extreme! Other than the cancer, I have not had any real side effects during or after the infusion.
Hope that helped!