ankylosing spondylitis
"Don't know why, but the Humira Pen injection is almost always super painful.  MUST be poor design.  I did self-injectiions with a string of Enbrel for 10 years, and it never hurt.  And after a recent hip replacement, I had Arixtra (blood thinner) injections that were completely painless.  

Why does the Humira pen hurt so bad?  

And I know it is not me, because I have read hundreds of other people complain about the same thing."