Why isn't polyethylene glycol working to relieve constipation?

[debodun]

68 year old female. Lately I've been extremely constipated. I go, but it's hard and difficult to pass and flush. I sent an email to my gastro and he recommended polyethylene glycol for relief. I tried it according to the container directions, but it didn't change anything. I emailed him again and he said that it might take more than one dose and to take it several days in a row. I've had 3 doses now and nothing has changed. Can it be that polyethylene glycol doesn't work for some people?

[debodun]

Oh...  it may take 3 days then?

[flyinlynn]

https://www.drugs.com/dosage/polyethylene-glycol-3350.html

Usual Adult Dose for Bowel Preparation
17 grams dissolved in 4 to 8 ounces of beverage, orally, once a day
Duration of therapy: No more than 7 days

Comments:
-The beverage may be hot, cold, or room temperature.
-Generally produces a bowel movement in 1 to 3 days.