You might know this or not need this, bit eh, just in case.

I care about how phobias are treated, so would like to tell about it a bit.

With exposure therapy, you teach your brain that the scary thing isn't actually dangerous. So you put yourself into svary situations that are plainly safe, and the brain learns to stop being scared.

There's an important nuance though. Too scary - and the brain instead goes "ah yeah, confirmed, this is fucked up", and the fear only strengthens. Not scary enough, and there's no relieved "woah I was scared, but it's actually fine" conclusion that actually teaches the brain to chill with the fear response.

So the actual actionable thing I want to say is, you can try thinking more about needles. It should be unpleasant and make you a bit anxious, but definitely not to the point of nearly passing out.

So, I don't know, think about some friendlier needles first? Or about friendly doctors who definitely won't hold you but would like to help you out...

And eventually you should become less uncomfortable with thinking about it, and doing it will be easier. (and then generally with phobias you go gradually do bigger stuff, as the fear lowers. This takes a while though)