My recollection is it took around 2-3 months for it to reduce inflammation. In my case, the 8 week intervals for injections were too long based on the level of drug in my system for therapeutic benefit by the end of the 8 week period. My GI is making effort to get insurance approval for six week injection intervals. I am unaware of any significant side effects from Stelara. I did notice a reduction with energy level but nothing dramatic.