What can I do to control side effects I will get from chemotherapy for stomach cancer?

Medication. Your oncologist will put you on prophylactic medication to counter some of the possible side effects from treatment. For example anti nausea med for nausea, anti diarrhea med etc. Maintain a healthy diet. Avoid sick contacts.
Quite a Lot. Follow doctors instructions closely- diet (everything cooked-nothing raw); nausea control (use meds as instructed before getting nauseous); proper fluid intake (to prevent dehydration); infection precautions (minimise contacts, hand sanitizers); daytime power naps or rests; daily light exercise/walking; use diarrhea meds aggressively; biotene/baking soda oral rinses; call for fevers immediately.

Related Questions

Uncle has stomach cancer. Doing Chemotherapy right now. What foods should he avoid? And what foods are good for him?

Emphasize healthy... Your uncle should emphasize nutrient-dense whole foods like fruits, veggies, nuts, seeds & eggs- see https://www.drfuhrman.com/library/what-is-a-nutritarian-diet.aspx Avoid sugar, fried foods and processed foods. Also see http://www.ncbi.nlm.nih.gov/pubmed/17283738 and http://tinyurl.com/l9pdmjd Good luck to your uncle. Read more...