I am taking 1000 ius every 4 hours and it is bringing me back to the person i used to be. I had accute sinusitus - 7 rounds of antibiotics over a 9 month period. After i cleared up a Bacterial infection, then learned self care stratagies for extreme allergies (South Texas Hill Country Cedar and mold) the doctor said if i still felt bad it was probably due to a virus. And he added there was nothing he could do for that. By a gift from God a woman stopped me (out of the blue) and began telling me about Lypo-spheric vitamin C. She said to go to vitamincfoundation.org for more info on the healing power of Vitimin C. I'm in my second week of taking it and my energy is restored and i believe i won't have to go back to doctors any time soon. Yeah!!! I'm going to continue my 1000ius every 4 hours for 1 more week then reevaluate how much i need to take. I had also boosted my glutathione levels earlier with Immunocal, but as i was fighting the bacteria in my nose/throat i had to eliminate all dairy for a while. But i don't think Vitamin c can be effective if glutathione levels in your body are low. Hope this helps somebody who has multiple heslth issues at one time. If can be confussing but hang in there and treat everything you can one step at a time. You will get better