I was given dexamethasone by IV at the same time as the FEC infusions, and domperidone and
granisetron to take home. I was advised to take the anti-emetics as prescribed, before I felt nauseous, and although I did have nausea, I had no vomiting. I was also prescribed Nystatin lozenges to hep with the thrush in my mouth. However, people do react differently to chemo, and as suggested by Cleveland Clinic response, the correct person to sort this out is your Mum's Oncologist.
Take care.
Liz.