I had about 20 sessions of pheresis. If you are lucky, like me, and they are able to use peripheral access in veins in each arm, then you will experience a little more pain than a normal IV needle, the needle gauge is definitely larger.
I had a fair amount of scarring and bruising from the needles. The procedure itself is painless, but you can get chilled. I typically had a pretty significant drop in blood pressure at the completion of each exchange, and would take about 10-15 minutes of sitting up, drinking some juice, eating a cookie, etc. to get it back up to around 100/70.
It did tend to wipe me out a little bit for the remainder of the day, but at the time I was having a serious CIDP flare, so I was experiencing lots of fatigue anyways. The pheresis itself was of modest benefit.
I’m in my mid 40’s, and besides CIDP, in good health.
Best of luck to you.