I was on chemo for 49 weeks w/Herceptin & my nail beds were a mess from the chemo killing off those cells!My nails continued to grow, but they were detached down to the nailbed & very sore! Since finishing chemo & continuing w/herceptin (7 & half months now)my nails are growing out nicely, healthy & pink,re-attached to the nail bed & white at the tips like normal nails!
I don't think the nail problem is a direct result of the herceptin-remember, it only targets the her2 receptors on tumors & some cardiac cells.I think it's more likely that the nail problem is a result of our bodies still trying to function as best it can while on strong drugs & rbc's & wbc's being compromised.Many people say their hair is growing in more slowly too.
I know,in the scheme of things, this is a totally tolerable side effect, but annoying none the less, like the whole weight gain issue!

no nail problem for me from herceptin, but i had major problems while on taxotere. finger nails turned brown and pulled away from nail bed - it took a year to grow out, but now they are fine.
el