Because I was warned about the constipation I started using Benefiber and so far no problems. I don't know any side effects. I have only had one week of treatments so not too many side effects yet. But then I wonder if maybe the patch is taking care of any pain that might be there.
Also, I believe that Tylenol taken too much or too often can be very hard on the liver but of course you might want to check with his Doctors about that.

55 12/17/09 High Grade Muceopidermoid Carcinoma Alerted by Largo my Mini Schnauzer
1/18/10 Clr PET
1/27/10 Surgery found Perineural invasion
3/22/10 Began Rad
05/05/10 34 rads
8/19/10 Clr Pet Scan
12/13/10 Clr Ultra sound/biopsy
5/4/11 MRI Clear
8/2/11 All Clear
5/25/12 All Clear
6/3/2016 All Clear