Onions and garlic both contain something similar to each other that works. I have found that as soon as I even suspect that I may have a cold coming on (the little ‘itch’ in the back of the throat), or know I’ve been exposed, I will start eating a few raw cloves of garlic a day. It always works so long as I get on it immediately and am consistent for at least 2 days, preferably 3. I’ll avoid the bug while the people around me turn into human Petri dishes.
I now crave onions when cold season arrives! I like garlic in cooked foods and some types of salad but I cannot tolerate large amounts raw with a problem arising related to diverticulitis, which my cousin cured years ago by feeding me salsa three meals a day for a week. He made the salsa , even roasting the various peppers in the oven to remove the skins. He made the best salsa I had ever eaten! And yes, he included raw garlic in it. ... And a little red wine is very good for the gut.
Allicin
Vitamin D. If a cold or flu has already started take 900 units per pound of body weight in one dose. That works out to 27 little tiny 5000 iu size gelcaps for me. First time for me I was very sick and everyone else was laid out for 3-4 weeks. My MIL handed me the D3 and said take it. I was fixed and fine in 8 hours. Now I take one of those things daily and have not had a virus in 16 years. No flu shots either.