 [ Symptoms ] my dad has stage 4 colon cancer with mets to the liver he stopped chemo 8 mo ago now having severe constipation prob he quit chemo because his body couldnt take it anymore my dad was taking milk of mag for 2 years as well as 4 stool softners a day  his major complaint is a constant urge to have a bm and severe cramping all the time we have recently started on miralax he was taking a capfull a night then he got diareah we backed off we just started taking the miralax every 3rd day we just started that last night he is on a huge dose of pain meds but he has been on the same meds for 2 years help [ Disease ] i am sorry to hear about your dad is cancer but how lucky he is to have you to help him through this it sounds like you have been doing a great job managing your dad is constipation as you know opioid narcotic pain medications can cause constipation the stool softeners were a good idea as was the miralax if the miralax was working but then caused diarrhea you may need to keep playing with how much and how often to use it in order to achieve the desired result if your dad is experiencing constipation you can give him the miralax even if it means you are off schedule with it do not get stuck in a schedule if it is not working because your dad has colon cancer specifically and he is now experiencing problems with bowel movements it would be a good idea to make an appointment to see his health care provider this increase in constipation along with the cramping could be related to the disease progression and should be evaluated by his primary care provider or oncologist i wish you all the very best as you go through this journey hang in there