How long will a dulcolax stool softener work? gave one to my son at 7pm last night and he is still pooping. do they usually last that long?

Sometimes: There is a possibility that the dose given was a bit much for him. No cause for alarm as long as he is active and well hydrated. Effect will definitely wear off in 1-2days

StartedSomething: The half-life (time it takes for the dose given to decrease by half) for dulcolax is 8 hrs. You gave your son a stimulant laxative to initiate bowel movements after a period of constipation, it stands to reason that they are going to continue to be moving until the lowest effective dose is gone.