The adverse effects reported at the top of this page are probably related to an increased need for manganese and B6 to form GABA and process sulfur. Obviously B2 is also needed (+magnesium, Potassium). in some of his texts Dr. Lonsdale says that B1 isn't supposed to be taken in isolation since it is part of a bigger picture (think Citric Acid Cycle).
My intention was to reach therapeutic levels with B1 but had to back off. I don't think I will tolerate it on it's own without B3 and folate due to the severity of the rash.
According to his book, Thiamine Deficiency Disease, Dysautonomia, and High Calorie Malnutrition, in some of his cases, Dr Derrick Lonsdale used a nutritional IV formulation that had equal amounts of thiamine HCl and niacinamide.