Hi, I had a lot of constiptation during chemo. I found out that my oncologist was giving me anti-diahreah meds with my chemo!
One time I was so blocked I had to take the prep stuff they give you for colonoscopy! Just awful!!!
So please check with the dr. to be sure you know everything they are giving him and the side effects for each. And ask dr. what you are allowed to take. I take colace 3 times a day for the first 3 days of chemo, then nothing as diahreah sometimes happens on 4th day.
I don't use any fiber stuff. It gives me pain and discomfort.
I think everyone is different and you will need to find what works for him. And you may need to adjust depending on diet and meds changes. What works today, may not work next week.