Is isphagula/psyllium a safe supplement to take daily for the management of chronic constipation?

Yes but can be gassy: People who eat lots of fiber tend to have lots of gas, as the undigested fiber is a picnic for billions of bowel microbes and bacteria. There are reportedly more billions of bacteria inside our bowels than the number of cells we have making up our own bodies. The bacteria will likely keep eating and keep making gas, as long as the fiber "food" keeps coming down the pipe.