I too suffered from it quite badly and it was affecting my ability to care for my daughter.

I tried:

Ginger tea - made from fresh root & hot water. Had some minor relief.
Vegemite toast - no good for me
Mints - no good for me
Eating a dry cracker and tea before I got out of bed each day - minor relief

Finally I went to a qualified, registered Homeopath! She helped me no end, it did not go 100% but enough so I could function semi normally.

I would also recommend acupuncture as a close friend of mine had it even worse than me and acupuncture was the only thing that relieved her of it. You do have to go quite a bit though, not just once or twice.

I had my last vomit at about 19 weeks so don't count on the magic 12 week end either.

Good Luck to her.