I took NDF once after I released a lot of mercury from antifungal use. I must have taken too much NDF too soon and I was almost bedridden for 3 weeks. I never got that with andy cutler's protocol, so long as I stuck to the frequent time dosing. If I messed up, missed a dose and continued on regardless, then I would experience redistribution and that would then cause severe effects.

I think people are afraid of Cutler's because it's medicated, (DMSA), rather than natural. But natural does not necessary mean that bad things don't happen. They do because you're dealing with a neurotoxin and the way this stuff is moved can cause severe side effects and it can easily be migrated into more sensitive tissues and into the brain.

Cutler's seeks to reduce redistribution and move mercury out more evenly and safely due to keeping the chelating agent levels even in the blood. This is why he recommends taking it every 4 hours (or more often if needed).

If you want to talk to someone about NDF, you may find this guy here of great help to you:
http://www.garylittleton.org/gl/content/view/31/31/

He took it and I think he tried NDF plus and had a horrific response to that, but I am not sure what happened or how he got himself out of it. He's used cutler's as well. He's done both, he'd be a good one to ask. He seems to have a great deal of knowledge about mercury and other issues and the best things to take whilst you chelate/detox and how to prepare etc.

I hope this helps.