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Thats really a good job you are doing at the same time I sad you have to do it for the sake of money. Well you need to be cautious as you are a young student frequent blood donation
can make you weak temporarily for one or two days. I am not discouraging you, but not at the cost of making money. There are various other part time jobs which you can choose. Finally, the veins from which the blood is drawn is usually a bigger vein which seldom gets thrombosed, do not worry.
Dr. Naveen Kumar