WTC: Who CAN'T give blood?

Factual Questions
21

Sadly all the pills I’m currently on for ADD and chronic
depression make my blood unusable. I’m especially upset because only 5% of people have my blood type. Besides the obvious problems with stopping my pills, some of the stuff won’t be totally out of my system for months.

 Dad can't because he's past the age cut-off. I'm sure he's upset about it. He used to donate as soon as the time limit was up from the last one. Mom got hepatitis B from a blood transfusion in the 80's. It's very frustrating. I'm too broke to donate cash or supplies, but I've got plenty of blood. I'd like to give it but it can't be used.
22

Is there any medical justification for this? Or is it a political-moral discrimination (read: PC)? I had a few pot brownies last month, but i doubt there’s a significant amount left in my bloodstream. [sub]Besides, a little cannabis might be good for an accident victim. :wink: [/sub]

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“Young man, summon your fortitude.” – Mark Twain