Hi Fredagail,
Welcome to the group. First, my question is, did the doctor try to treat your mother's diarrhea with anything? Velcade works very well. I would think that the doctor would try to treat the diarrhea before giving up on the meds.
How old is your mother?
Unfortunately, everything has side effects and we have to try to control them somewhat before giving up on that medication. I was on Velcade for almost two years (including the chemo before transplants and maintenance). I did have the diarrhea and practically lived on immodium for a while. I also have neuropathy. I never had to take anything for the neuropathy, but I've heard that there are meds you can try for that.
In answer to your question regarding lowering the dose of Velcade - yes it can be lowered. My was lowered, but I was already in remission. My dose was lowered a couple of times and at one point I was told it could not be lowered any more because it would have no value for the MM. So, there is a point at which the Velcade would not do any good. I was also given a longer break in between doses a couple of times, so my body would heal.
Is your mother seeing an MM specialist? They know all the side effects of these medications and may have treatments for them.
I always asked myself the question: Is is worth dealing with the side effects to get better? My answer was always, yes. It's better than the alternative.
Good luck. I'll pray for your mother.
Lois