What would cause tachycardia and intense beating of the pulse after giving blood (2 vials)?

Question

I thought a reduction in blood supply would result in lower blood pressure, but experienced the opposite: high blood pressure. Would an infection from the needle/pathogens cause these symptoms?

Answer 1

No, infections need time to take effect. My guess is you had some minor anxiety about the blood that was drawn, and that sped up your vital signs. This is not a professional medical opinion.

Answer 2

if it was immediately afterwards it wouldnt be infection as that takes a day or two to develop and unless your in third world country chances are the needle was sterile and single use.

It could be a reaction to a couple of things.... one is the ethylene oxide gas used to sterilize the device. Some people (very rare) react to the residuals of that.  Or could be an anxiety thing seeing the blood or feeling the needle.. lots of people are affected by that.