Hi Tinlizzy, Not bragging here, but I am somewhat of an expert when it comes to laxatives, (Hey, we all have to be good at something!) having spent most of my adult life with chronic constipation. Those days ended three years ago, when I got my ostomy. Anyway, most laxatives will have a diminishing effect, as your body develops a tolerance for them. Even so-called 'natural' laxatives, like senna, will not work as well the longer you take them. If you are wanting something that you use long term and safely, without developing a tolerance, polyethylene glycol or PEG, is my recommendation. It directs liquid into your bowel, instead of just eliminating it. It is sold under lots of different brand names, a couple that have been mentioned here, Miralax, LaxaDay. It's also sold here in Canada in a few different no-name brands. I know Wallmart and Shopper's Drugs both have their version of no-name PEG. Just make sure to check for the name of the active ingredient. There shouldn't be anything else in it but polyethylene glycol. It's a powder you just mix with water and drink. You will need to experiment with the dosage to see what works best for you. Good luck!
Terry