Why does eating raw onions make me feel sick?!
If you don't usually eat a specific food, it can cause stomach upsets. Raw onions would especially be likely to make you feel gaseous and nauseus. Moderation with any food is always wise. However, the onion has many medicinal qualities.
Maybe it's just psychological, maybe you're allergic to them, or maybe you're getting sick.
When I was in college, they had a pasta station where the guy would take ingredients from containers (just sitting there, not really hot/cold) and put them in pans and cook it. I never got onions because they were always barely cooked and tasted like feet. Ick.
Raw onions can be pretty strong it doesn't surprise me you feel sick. Some people just don't have the stomach for raw onions.
Onions are very acidic. Eat some anti-acids, drink lots of water.