What is isadvantage of blood donation?

Blood donation: Most of the benefit is for the recipient of your blood and that in itself is a benefit. However, sometimes if your blood count is high, donating blood can make your blood less viscous (thick) and therefore beneficial to circulation.

Few if healthy: I am assuming the message reads 'disadvantage'. If so then the disadvantages are: mild pain at the needle site, volume loss replaceable with oral fluids; iron loss replaceable with oral iron supplements. It is the 'gift of life' for the recipients.