Faintness after blood samples taken - what's really going on here?

I spent the morning in hospital having my arm looked at - my elbow became inflamed and extremely painful/tender in the space of about 18 hours (diagnosed as bursitis with possible infection - antibiotics and horse-pill anti-inflammatory prescribed, and I’m starting to feel better already)

Anyway, during the process they took a couple of blood samples for analysis for infection and gout markers - almost immediately after this, I felt nauseated, giddy and clammy, and experienced a sort of buzzing/tingling sensation in both hands.

I’ve only ever had blood taken once before - a couple of years back (that time, it was half a dozen separate little tubes, but still not a big volume in total) and the exact same thing happened then.

And I’ve experienced the same set of symptoms before in the past in other circumstances - as a precursor to fainting (or nearly so).

So what’s going on here? Can it be that losing a few tens of ml of blood dropped my BP enough to make me feel faint? Or is it just an emotional/psychological reaction to losing a bit of blood? (I watched it happen in both cases, but with mild curiosity - no particular fear - and I don’t despise or fear needles, as a general rule - don’t like 'em, but not afraid either).

Why did I nearly faint after having a small amount of blood taken?

I knew someone who fainted if you just said the word “blood”.

It’s psychological (surge of stress hormones then the comedown from them) or an old evolutionary thing.

Once somebody “learns” the reaction, it’s hard to get rid of.

Is it normal for that to happen without any accompanying mental/emotional effect? (I felt quite calm about it )

When I get blood drawn I have to do something like recite the alphabet or do arithmetic out loud, or else I will faint dead away. Like you, I feel perfectly calm, I feel no kind of fear or revulsion about the blood draw. But thinking about blood siphoning through things for some reason always sets me off, and getting blood drawn is an instance of that.

It seems to be purely physiological.

I’m sure it’s entirely psychological.

This happens to me occasionally. When I was younger, it happened more often. I think if you get blood samples taken often enough to “get used to it” (even just once a year may be often enough), it becomes less of a problem. This is known as “desensitization”.

I have the same problem occasionally, and a little more regularly, with getting shots. That always squicks me out. But I never have that problem with the annual flu shots (just slightly the first time I got one).

The first time (as an adult) I got a tetanus booster (1976), I spent about four hours nearly fainting. Every ten years ever since, no problem. I didn’t have a problem with the shingles shot a few months ago, but I fainted after the pneumonia shot a year ago. It was a long shot that took about a minute!

[Story time!]
I wonder if lab technicians, when I was a young child, taught me to be queasy about blood draws. In those days, I went right to the lab, they took the blood draw there, and immediately smeared some out on a microscope slide, put it under a microscope, and started counting. They always let me look through the microscope too. But when the technician (always a female person) drew the blood, they would always say something like:
So I think I picked up from that, that blood draws were something that I was supposed to be scared of and squicked out about.
[/Story time!]

You’re having a vasovagal episode (basically a precursor to fainting). Lots of things can trigger the vagal nerve, including seeing blood.

I suffer from the same thing- mentally/consciously I have no issue with blood and actually find medical procedures very interesting… but on the couple of times where I have given blood, I’ve had the same symptoms: nausea, ringing in the ears, sweating/ feeling flushed, etc.

It actually really bothers me as it seems to be a horrible evolutionary disadvantage: I envision being seriously wounded and instead of being able to treat my own wounds- I just pass out and die. Other people’s blood doesn’t seem to have the same effect. It also seems worse if the phlebotomist has a problem with sticking the vein. If it’s over and done with quickly, no issue. If it takes a try or two, it seems to catch up with me.

Ditto about vasovagal response.

If you feel it coming on then you should lie down. Should help.

Really? It’s purely psychological? What if it only happened once? I’ve given blood many times; 99% of the time I feel fine, but there was once where I was genuinely concerned about not making it over to the cookie/juice table. And then I was happy to sit for a while.

“a female person”? How about just a “woman”?

I recently had 10(!!!) tubes drawn for some pre-op testing and felt terrible following. My GP told me he thought it was an anemic reaction to the loss.

I’m like this too. I get blood drawn every three months. I lie down during the draw, and drink some orange juice right afterwards. It helps me a lot.

I’ve also learned that the blood draw is quicker and easier if I’m well hydrated, so I’ve started drinking more water in the morning before the appointment.