I personally must avoid onion at all cost. In the raw form just the juice on say a hamburger bun can put me into anaphalactic shock. Even in it's cooked form it still will make my tongue swell up and break out in ulcers and make me vomit. Onions, peppers, leeks, garlic are all related and if you have a truly severe allergy to onions, a reaction can be triggered by any of these other items in the same family. Get used to saying "I ordered this without onions...NO, you can't just pull them off the bun, you've got to remake the WHOLE sandwich again" lol Thank God for Epipens and benadryl and steroids