Well, Crohns is not contagious so you can't give it to anyone by blood donation. I know a lot of doctors discourage Crohns patients from donating blood, largely I think because we tend to be anemic anyway. Also, I suspect some of the medications used in Crohns -- remicade, immuno-suppressants and of course steroids -- are among those that blood banks have on their "do not take" list. Overall I suspect the "don't donate" decisions are more about
our overall health, and I recall seeing some posters here in the past say they can and have donated.