I take 2 oz of aloe vera every day to relieve ibs-c and it is very helpful. is there any side effect to my digestive system such as melanosis?

Not with gel but...: This depends on which part of the plant is used.The inner gel is quite safe, but the skin, used as a laxative, contains anthroquinones that can cause melanosis (though that is not necessarily serious). See http://www.Ibsgroup.Org/forums/topic/158584-why-i-stopped-taking-aloe-vera-juice/ (scroll down-the top part is misleading as the first posters don't get the diff.). Also see http://bit.Ly/19ymyl0.