As a fellow member- i have to say that I prefer oregano oil over the Grapefruit seed extract.
While the grapefruit seed oil has anti-viral properties- you probably get better benefits if you use an entire bottle of it --whereas with Oregano Oil, you just need a few drops every hour under the tongue.
Oregano Oil has killed many nasty things immediately for me-- including sinus parasites colds, a minor flu last year. It killed them within 5 minutes.
I do also have Grapefruit seed extract. I have them in tablet form with herbs mixed in. Just paid $10.00 for the bottle. One tablet is equal to 25 drops of grapefruit seed extract.