Hi Lolasana, from what i gather from Rich he suggests that MB12 alone can cause excitotoxicity if dose is too high. I had symptoms of excitotoxicity when i first started injecting MB12 at 500mcg a day so i reduced to 250mcg every other day for 3 months, i have recently upped it to 300mcg a day. I dont take any of the co factors at the moment. Fredd on the other hand describes these symptoms as start up and says you mustnt reduce your dose and must push through - he says this is not excitotoxicity. For me persoanlly i know my body and i never like to push through anything - doing this in the past has made me very ill. I always back off and slow down. Rich suggests switching to Hydroxy and trying liposomal Glutathione, although of course Fredd says no one should take Glutathione (i dont know why) I think its a matter of choosing which approach you prefer/trust/works for you. All the best, Justy.