I have an anecdote there: I got this medication that didn't help so much, so one of the nurses (bless her) switched me to something else, and that worked great. This after exclaiming:

But this stuff relaxes your stomach! You don't have that anymore, I will give you something else.

The stuff I got after that worked great. The next time they wanted to give me that other stuff again, but I and TG protested heavily and I got the other stuff again. They also turned down the epidural (took away one of the opiates) to help with the nausea.

It never went away completely.

Now that I've removed certain foods from my diet (wheat-products and milk) and have stopped taking the Plaquenil I have a lot less nausea. It hasn't gone away completely (yet), however, it has gone away a lot. Instead of mostly nauseous with some nausea-free hours, the reverse happens most of the time. I only have the last week or two to look at, so I won't yet do a little victory dance. It looks good, though, and that makes me happy.