Bruising
Although we hope that no donor will have any ill effects from giving blood, occasionally bruising of the arm may develop. The bruise can look very dramatic and some people may find this worrying, especially if it appears away from the donation area or is not visible until the next day. Bruising can look very nasty, but it is usually harmless and will disperse with time.
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Fainting
It is important to be aware that some donors feel faint after giving blood. During blood donation 8-10% of the blood volume is removed. Most people adapt quickly to this loss and their system is not upset by it, but a few individuals adapt less well and consequently feel faint. We hope this will help explain why some donors feel faint after giving blood.
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