Problems from long term use of Miralax

My Dad has been on daily doses of Miralax for over a year to combat constipation from PD. He recently had an impacted bowel, which took a week to clear. He appears to be going regularly now, but is now been on 2 doses of Miralax a day for a week. He’s experiencing cramping now and I think it’s due to too much Miralax.

Studies have been done that show the ingredients can be harmful to kidney patients. Could this be the case here?

I am not a doctor. I’d suggest that your father talk with his doctor about his constipation and other problems that he is having and what he should do/take for those problems. The Drugs.com site says Miralax should not be taken more than once a day and it is for temporary use…up to 7 days unless a doctor advises differently. Another option his doctor may suggest is Metamucil. Here’s info about how Metamucil and Miralax compare. It says Metamucil can be taken 1-3 times daily every day.
https://www.drugs.com/medical-answers/metamucil-miralax-compare-3562488/

This site says what to report, including severe stomach pain, and it lists common side effects including bloating, gas, upset stomach, dizziness and increased sweating.
https://www.drugs.com/miralax.html