I've been on Remicade since 2012, experienced zero side effects, but have found a remission.
We're all a little concerned when considering a new class of medications. Myself included. What helped me was looking at the actual risks versus benefits of those side effects that scare us spitless. The most concerning side effect of these medications is lymphoma which has odds of 6 in 10,000 (or 0.06 percent) when you are concurrently on immunomodulators (6mp/Imuran/MTX), compared to 2 in 10,000 ( or 0.02 percent) for the general population (average healthy folks without any medications). What happens to those who do get the lymphoma? 66% are able to put it into a remission. So you are talking very, very long odds and it is nothing to loose sleep over. The benefits far outweigh the risks.
A lot of the current research points to the immunomodulators being the actual cause of the lymphoma risk, not the biologic. As all of those in the early clinical studies of biologics who got the lymphoma were on the immunomodulators concurrently (nobody was only on biologics and got a lymphoma).
The Crohn's and Colitis Foundation of America is the source for these statistics. If you would like to take a deeper dive into risks versus benefits then watch/read the following. It helped me greatly.
Moderator Ulcerative Colitis
John, 39, UC Proctosigmoiditis
Rx: Remicade @5mgs/kg/6wks; daily 75mgs 6MP, 4.8g generic-Lialda, and rowasaSevere flares make the common toilet worse than any medieval torture imaginable. The rack? Bah! I survived the thousand razor blade poop for weeks!