Glutathione is actually an antioxidant. The whitening of the skin is just a "side-effect". Taylormedicalgroup.net says the recommended dose is twice a week. And since it's an antioxidant, results will probably seen faster if you have lower levels of toxins in your body -- this means you should avoid smoking or drinking or taking/doing anything that will increase the concentration of free radicals in the body.
Visit taylormedicalgroup.net/iv-nutritional-therapy/glutathione-skin-lightening-iv-injection for more information