Should I feel dizzy this long after a blood test?
April 14, 2009 8:12 PM   Subscribe

I had blood drawn seven hours ago for testing. It was one or two vials, not very much. I feel really dizzy now. Is it normal to feel dizzy this long after a blood test? What could be causing this feeling?
posted by anonymous to Health & Fitness (15 answers total)
Maybe because you're anxious about the results? Or you're squicked by thinking about about having blood drawn? It's not because of blood loss.
posted by moxiedoll at 8:23 PM on April 14, 2009

Yes, it could by psychosomatic.

However, (smaller) women with low blood pressure can be susceptible to some extra adverse effects. Easily remedied by staying hydrated and taking it easy.
posted by porpoise at 8:27 PM on April 14, 2009

Did you eat before blood was drawn? How much have you eaten since? I've heard that its good to eat some red meat (oddly enough I had my blood drawn today for a vitamin D test and I felt the same way for a few hours. After eating carbs and some lamb I felt a lot better....) Feel better!
posted by Eudaimonia at 8:27 PM on April 14, 2009

Have you taken in food and liquids? I have never felt dizzy so many hours after a blood test, but they always force you to eat and drink after blood donations. If you've been exerting after the blood test and haven't eaten much, I wouldn't be surprised about the dizziness. Try eating and resting.
posted by bread-eater at 8:28 PM on April 14, 2009

Seconding anxiety. I've only given blood once and I straight passed out the second I saw the vial filling up. The reaction was so fast there is no possible way it was physiological. My vision started getting greyish brown around the edges and grew to a pinhole and then I was gone. The nurse told me this was super common and gave me a cookie.

I had no idea I had an aversion to seeing my own blood and would've laughed off any suggestion seeing it would affect me so. It's either a primal reaction some people have or perhaps it touched some buried memory of an injury from childhood (I know I cut an artery in my foot when I was young but cannot recall it).

So what I'm saying is, don't discount a base psycological reaction causing this discomfort. IANAD obviously, but I doubt two vials of blood would affect your blood sugar in any substantial way.
posted by cj_ at 8:31 PM on April 14, 2009

Are you sick? As in, could the dizziness be related to the reason why you had blood drawn in the first place?
posted by JuiceBoxHero at 8:31 PM on April 14, 2009 [1 favorite]

(That should say blood pressure, but I guess blood sugar would work too. Again, not a doctor, but I'm sure eating and drinking something would set you right pretty quick if the dizziness is from that)
posted by cj_ at 8:34 PM on April 14, 2009

How's your blood pressure? Whenever I get dizzy, eating a banana and drinking gatorade usually helps.
posted by aquafortis at 8:56 PM on April 14, 2009

they always force you to eat and drink after blood donations.

yeah but when you donate blood they take quite a lot (~470 mL apparently) whereas one or two vials for a blod test will be 10 mL or less. We're talking two teaspoons of blood, not enough for the blood loss to have a physiological effect. So it's either psychological or caused by something else. I've had a bad head cold the last few days and feel dizzy occasionally because of that so yeah, maybe look at why the blood was being taken in the first place?

Eating and having a drink will probably make you feel better anyway, but if this continues or you have other symptoms like nausea maybe ring the doctor's office and see what they think?
posted by shelleycat at 9:07 PM on April 14, 2009

I once vomited and almost passed out after giving blood because I forgot to eat and they didn't remind me. Have a snack and hydrate.
posted by cestmoi15 at 9:08 PM on April 14, 2009

From the phrasing, you've only just started feeling dizzy, yes? You were feeling fine in, say, the hour after the blood draw?

That would suggest that it's not related to fluid balance or blood sugar, because they would have come up earlier. Unless this is a test that you've been stressing about, and you've forgotten to eat and drink since the test - in which case, have your dinner, glass of water, see if you feel better.

Juiceboxhero has a good point about dizzyness possibly being related to what you were having the blood taken for - dizziness can be a feature of, for example, anaemia.

Psychosomatic is a possibility as well, as is it being something entirely unrelated (like you're coming down with a cold).

Keep an eye on yourself, and call the doctor if it gets worse.
posted by Coobeastie at 3:08 AM on April 15, 2009

While I'm not a smaller woman with low blood pressure, I have experienced this on one blood draw in particular. The technician hit or tugged on a spot inside my arm that almost made me pass out at the time, and i was a little weird feeling the rest of the day. It didn't hurt, it was just a strain kind of feeling. Like that weird feeling in the pit of your stomach when you break a bone.
posted by gjc at 5:12 AM on April 15, 2009

Hypoglycemics shouldn't give blood, because this is a mild example of what happens to us...

... speaking from hideous experience.
posted by IAmBroom at 7:40 AM on April 15, 2009

I come within || <- that close of completely passing out any time I am stuck by a needle. I turn pale, get tunnel vision, and my hearing gets all weird. It usually doesn't happen until after the blood draw (or whatever) is all done.

It seems to be a reflex, because there is no conscious thought involved. It has happened when I got a vial of blood drawn (several times, whether I was watching or anticipating it or not); it happened when I got flu shots; it even happened once when I sliced my finger open with a knife.
posted by ArgentCorvid at 7:46 AM on April 15, 2009

I feel dizzy or light-headed all day after I have my blood drawn. Maybe it's purely physiological (small woman with low blood pressure here), maybe it's purely psychosomatic (strong fear of needles here as well).

If it's not gone tomorrow, maybe you should check with a doctor.
posted by medusa at 4:49 PM on April 16, 2009

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