That's what I use, Hills. And it's practically impossible to overdose with Vit C. But for it to work for a cold or other viral infection, I find I need to take 1,000mg every 2 hours for 48hrs. If you're lucky, it nips it in the bud. It works better when taken at first sign of symptoms. If the cold or whatever has got a good start, it's not so effective. I have recommended it to scores of people over the years and lots of them have got back to thank me as it worked brilliantly! Can't recall where I got it from originally, a friend I think.