I take Flomax daily and have used Cialis, although I currently use Viagra. I have noticed no diminished effects of either drug (Cialis or Viagra). However, Flomax can have an effect on the volume of semen you produce due to a known side-effect called retrograde ejaculation. This side effect is caused by the way Flomax works on the prostate and results in the semen flowing into the bladder rather than down the urethra.
I'm not sure if this is what you mean by "isn't working like it used to", if it is, then you have an answer. If you are refering to diminished erections talk to your doctor and maybe switch to Generic Cialis. (I will say that I have had one or two experiences in the 5+ years I have used an ED drug that I still failed to maintain an erection. Sometimes shit happens!) I also notice that when I am tired or hung over, sometimes it's harder for me to get and maintain a rock hard erection

TallMan2356