Blood Pressure, Low Acceptable as long as you feel well when you come to donate.
If your blood pressure normally runs low, it may be more difficult for your body to adjust to the volume loss following donation, especially if you are dehydrated.
Age You must be at least 17 years old to donate to the general blood supply, or 16 years old if allowed by state law.
There is no upper age limit for blood donation as long as you are well with no restrictions or limitations to your activities.
and it doesn't even matter enough to get a nice little letter from my government saying.."scuse me but if you're feeling a bit fuzzy in the mornings and losing your temper a lot and falling down constantly..