You can take fiber (psyllium) indefinitely...although you may not want to take higher doses of it...it won't harm you, but you'll probably get tired of taking the shakes so much. Adding liquid Bentonite will make the cleanse much more effective. For an initial Colon Cleanse 6 months is about max...if you're still getting significant quantities of mucoid plaque. You'll see a lot more of it with the bentonite.