Open Question: dose all chemo make you sick ?

So please find my mother today she will begin chemotherapy, her doctors said she would use the most simple types, they are most they told her it was to prevent future cancer of the Cuz from the first phase of her breast cancer, but IM-a medical freak, want to know exactly how it works and how to make you think it dose dose of hair is always falling? They told her that she just used to feeling tired, sick, weak, and where the opportunities for her habit of hair loss