Mineral+fluid intake during blood donation

[EnumaElish]

I try to give blood a few times every year. What's been bothering me is the feeling of weakness/dizziness/nausea right after the donation. Drinking lots of fluids afterwards (water, fruit juice, sports drinks) helped, but I continued to feel weak and tired throughout the day.

Today I've decided to run an "experiment" and brought a 2-qt. bottle of homemade "sports drink" (water, pear juice, salt, sugar, mineral water with lime flavor) with me to the donation center, and sipped it while they were collecting my blood. Afterwards, I felt almost normal, with almost no weakness or dizziness; it's nearly been "just another day."

[mgb_phys]

I always feel dizzy - even faint if I don't stay lying down for 10-15mins afterwards.
I think it's psychological, they only take 500ml and I have more than enough body mass for that to be negligible!
I guess they don't want people drinking while they donate because you are lying down and might choke or disturb the needle if you sit up to drink.
I will have to try drinking an extra litre of water immediately before.

[MATLABdude]

I think the average person only has 5L of blood to begin with! I get pretty severe nosebleeds sometimes, and it always leaves me feeling a little weak and woozy for a few hours afterwards.

[leroyjenkens]

My friend goes to the gym with me sometimes right after giving blood. But he's a big guy and has a lot of blood left.

[EnumaElish]

For the record, they put me on a recliner kind of chair. I wouldn't have attempted it if I was lying down.