The 31-year-old defensive end underwent shoulder surgery earlier in the off-season, having sustained a labrum tear last November.
Allen told NFL AM: "Unfortunately, yes. I was hoping to get a couple weeks of training camp off, but the training staff is pretty good here. So I'm ready to rock 'n' roll.
"Honestly I'm just focusing on my shoulder right now. Like I said before, I think I'm kind of in a blessed place where both sides are honoring the contract that we signed. Whatever happens will happen, but my focus is just on football."
Allen made 45 tackles including 12 sacks for the Vikings in 2012.