bayou girl, as the others have said, they do a really good job of pain management in the hospital. Each of us is different after that. When I came home, I needed some pain meds for a week or so - about half the recommended dosage, and only at night. I was up and around the house all day, and the gentle movement seemed to help manage pain. The only "real" pain I had was when I coughed or sneezed. (I had a nasty cough for 6 or 8 weeks after surgery. It turned out to be a side effect of one of my meds. Changed meds, cough went away.) They teach you in the hospital how to support your sternum if you sneeze, and as long as you remember to do that, it is manageable. Not fun at first, but manageable nonetheless.
As for the impact of the pain meds on your digestive system, we're all different. Those meds were a real problem for me. Between the meds I was given at the hospital and the ones I took at home, my system came to a complete stop and stayed there for weeks. It got so bad that at 4 weeks post op, I was readmitted to the hospital for a few days to get it all regulated. They gave me an "industrial strength" laxative (magnesium citrate), which did its job. They then sent me home with instructions to take Miralax (an over-the-counter laxative) at full strength for a week, then half strength for a week, then quarter strength for another week, by which time they felt I would be back in normal control. It worked, but it could have been avoided had my medical team advised me to use the Miralax at first sign of trouble. Other folks here have said that their doctors have advised them to keep Miralax on hand for their return home, and to use it before problems arise. It probably makes "those things" easier on your core muscles when you're healing, and certainly is unlikely to cause any trouble.
So, pellicle uses kimchi. I used Miralax. They seem to do the same thing. Just be aware of your body and take steps to keep things from getting out of control and you'll do fine.