…the best cure for a common cold is mega-dose vitamin C, taking around 1 gram an hour, or 2 grams every two hours, until symptoms abate.
The goal is to get your blood level of vitamin C as high as you can without extremely loose bowels (known as bowel tolerance level) and keep it up until you overcome the infection.
Then, I recommend having at least 4 grams a day for a day or two, before returning to what is my baseline of 2 grams of vitamin C a day. The vitamin C I take contains zinc and black elderberry extract. Echinacea is also helpful if vitamin C alone is not enough to win the war.
I assume this product is the one he means. For the higher dose Vitamin C, if you need it, it’s easiest to take a powder and you want a buffered version so it is gentle on your stomach. I like this one which gives a good dose of calcium at the same time which can be very calming when you’re feeling rotten!