How long does it take for the side effects from chemotherapy to begin?

A.brandt asked...

My dad is 62 years old and just got diagnosed with stage 4 lung cancer that has spread into his bones. We all knew he was sick but this diagnosis just came about 3 weeks ago. 1 of his doctors wants to start hospice as he thinks my dad will not make it through chemo and the other wants to proceed with some chemo treatments to see if they can extend his life a little bit. He only weights 112 lbs right now and is already very weak. I was nervous about him starting chemo but he had his first treatment today and is doing very well. My question is: Is it a good sign that he is doing so well right now or will the side effects start coming within the next few days or weeks?

Expert Answer

Andrew Putnam, M.D. is a Palliative Care physician at Smilow Cancer Center at Yale New Haven Hospital and Yale University.

The onset of chemotherapy side effects depends on the chemotherapy and the individual. Sometimes side effects start within a day or 2 of starting chemotherapy and at other times they can start several days later. Being fine at the start is a good sign but it does not mean that the side effects will not start later. Sometimes the side effects can be quite delayed and start days to weeks later or even during a later round of chemotherapy. It is important to ask the oncologist before the start of chemotherapy what are the likely effects. If something different happens during the chemo, it is important to tell the oncologist as it might be an unusual side effect.