# Why did I black out when giving blood (when everyone ELSE was fine?) **URL:** \ **Category:** Factual Questions\ **Created:** [July 18, 2003, 2:19pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391 "2003-07-18T14:19:25Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![JKB](https://avatars.discourse-cdn.com/v4/letter/j/7feea3/32.png) [@JKB](https://boards.straightdope.com/u/JKB)\ **Post date:** [July 18, 2003, 2:19pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/1 "2003-07-18T14:19:25Z")
Went to a blood drive earlier this week, and nearly fainted afterwards while everyone else was just fine. Why? I wasn’t nervous and blood/needles/medicinal stuff doesn’t bother me. In fact, I was chatting and joking around with the other doners as they disconnected the bag, feeling fine then suddenly, WHOOSH! Blackout time. My mouth/throat went dry and I was soaked in sweat too. (oh, the shame). Everyone else was fine. Do some people physically overreact to minor blood loss? I don’t get it. Why was I such a wimp? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [July 18, 2003, 2:24pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/2 "2003-07-18T14:24:21Z")
Is it possible you’re somewhat anemic to begin with? That would certainly explain it. ---
**Author:** ![Lynn\_Bodoni](https://avatars.discourse-cdn.com/v4/letter/l/e47c2d/32.png) [@Lynn\_Bodoni](https://boards.straightdope.com/u/Lynn_Bodoni)\ **Post date:** [July 18, 2003, 2:30pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/3 "2003-07-18T14:30:03Z")
Well, \*\* Q.E.D.,\*\* back in the days when I could give blood, they always tested my iron before even starting to take blood. **JKB,** had you eaten recently? A GOOD meal, not just a sugary snack? I’m thinking that maybe your blood sugar was a tad low. That’s the reason why they have juice and cookies at the center, you know. I am not a doctor, nor do I play one on TV. ---
**Author:** ![Podkayne](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@Podkayne](https://boards.straightdope.com/u/Podkayne)\ **Post date:** [July 18, 2003, 3:41pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/4 "2003-07-18T15:41:22Z")
I have the same problem. I am not frightened of needles. I feel no anxiety or distress when I contemplate having blood drawn. Although I have eensy-weensy, deep, jumpy veins and they often have to do quite a bit of prospecting to get any blood out of me, the pain is not particularly intense, and I am not apprehensive about it. Nevertheless, start poking me with a needle and I get woosy. It’s been a few years since I actually passed out, but that is probably in large part because I tell the nurses and techs that I have a tendency to get lightheaded, so they always have me lay down and treat me with kid gloves. I passed out once a looong time ago when I cut myself, too. It didn’t hurt a lot, and I wasn’t bothered by the sight of blood. I was just standing there, unconcerned, while someone put a bandaid on my finger, and then I said, “I feel kind of–” and keeled. Luckily I was standing in a crowded kitchen and about three people caught me before I hit the floor. Nothing like that has happened since, again, probably because I am now very careful, and if I get a deep cut, I _sit down_ immediately, even if I feel fine. I’m healthy as a horse, otherwise. Never had any trouble with anemia. Just not so good with the blood-letting. ---
**Author:** ![Podkayne](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@Podkayne](https://boards.straightdope.com/u/Podkayne)\ **Post date:** [July 18, 2003, 3:44pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/5 "2003-07-18T15:44:46Z")
By the way, **JKB** , if you have to have blood drawn in the future, be sure to tell the person that you’ve passed out, even if it is a bit embarassing. They are really grateful when you tell them, because they hate to have patients fall down and hit their noggins. ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [July 18, 2003, 3:48pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/6 "2003-07-18T15:48:20Z")
Yep, happened to me too, and about and hour or so after lunch. The lady there put it down to low blood presure but I’m a little skeptical. ---
**Author:** ![Eva\_Luna](https://avatars.discourse-cdn.com/v4/letter/e/e495f1/32.png) [@Eva\_Luna](https://boards.straightdope.com/u/Eva_Luna)\ **Post date:** [July 18, 2003, 4:18pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/7 "2003-07-18T16:18:07Z")
It happens to me sometimes, and not always on giving blood. The last time was in my ortho doc’s office, as he was injecting synthetic cartilage directly into my ankle joint (NOT fun, even with a local anesthetic; the syringe is pretty big and terrifying because of the viscosity of the stuff he was injecting, plus he had to do it slowly to make sure it distributed properly throughout the joint capsule). I started sweating, got dizzy, the whole nine yards. I didn’t pass out because I managed to lie down on the table, but it was a close call. The doc called it a “vasovagal response,” and said it was just one of those things; sometimes people react badly to having their body integrity disturbed. You’re just lucky, I guess. It may happen to you again, and it may not. ---
**Author:** ![CrankyAsAnOldMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crankyasanoldman/32/11670_2.png) [@CrankyAsAnOldMan](https://boards.straightdope.com/u/CrankyAsAnOldMan)\ **Post date:** [July 18, 2003, 5:33pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/8 "2003-07-18T17:33:22Z")
First of all GOOD FOR YOU for donating. Low blood pressure is a very good guess. I have nice low blood pressure. This is wonderful most of the time and was great during pregnancy. But it gives me problems when it comes to giving blood. The only way I can donate is to drink a lot of fluids for at least a day beforehand, and make sure I’ve eaten recently when I donate. Even then, I spend the rest of the day feeling completely worn out. My husband has borderline high blood pressure. He can give on a whim, fill the bag in no time, hop off the table and walk away and feel no effects. ---
**Author:** ![Podkayne](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@Podkayne](https://boards.straightdope.com/u/Podkayne)\ **Post date:** [July 18, 2003, 6:03pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/9 "2003-07-18T18:03:38Z")
Another piece of data: I also have borderline high blood pressure. Go fig. ---
**Author:** ![GilaB](https://avatars.discourse-cdn.com/v4/letter/g/8e7dd6/32.png) [@GilaB](https://boards.straightdope.com/u/GilaB)\ **Post date:** [July 18, 2003, 7:20pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/10 "2003-07-18T19:20:38Z")
I have lowish blood pressure (100/60 when I donated this week, but that’s a tad high for me), and never have problems with wooziness or fainting when I give blood. Normally I don’t feel anything at all; most recently I felt the very slightest bit lightheaded the couple seconds after I stood up, but nothing that would throw off my balance. Between that and Podkayne’s borderline high bp, I doubt that it’s just a matter of blood pressure. ---
**Author:** ![troub](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troub/32/14802_2.png) [@troub](https://boards.straightdope.com/u/troub)\ **Post date:** [July 18, 2003, 7:32pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/11 "2003-07-18T19:32:13Z")
I _don’t_ have high blood pressure, and I can usually fill the bag in just a couple of minutes, “hop off the table and walk away” also with no ill effects. I usually make an effort to ensure I’ve been drinking enough fluid before I donate–I think it makes a difference. Once, I tried not drinking so much water beforehand since I had been filling the bags up so quickly. It took a loooong time that time to fill the bag (a loooong time for me is probably what’s “normal” for others, in my observation). So, the next time I tried to make sure _that_ didn’t happen again, and drank lots and lots and lots of water beforehand. Again, my blood pressure was measured as being normal right before the donation, but when the nurse stuck me with the needle I **squirted** blood about 3 feet across the floor. Again, the bag filled up very quickly :D. I would agree with [vasovagal response](http://www.aafp.org/afp/20010515/tips/7.html). I often get lightheaded when having stuff _injected_, but usually not when having fluid removed (the exception was once when I was ill). ---
**Author:** ![troub](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troub/32/14802_2.png) [@troub](https://boards.straightdope.com/u/troub)\ **Post date:** [July 18, 2003, 7:34pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/12 "2003-07-18T19:34:39Z")
Also, [this link](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1661644&dopt=Abstract) notes that: > [@](#): > > Vasovagal responses are not necessarily abnormal; the neural pathways involved in the vasovagal response are probably present in all healthy subjects who **individually mainly differ in susceptibility.** (bolding mine) ---
**Author:** ![Bravic](https://avatars.discourse-cdn.com/v4/letter/b/ba8739/32.png) [@Bravic](https://boards.straightdope.com/u/Bravic)\ **Post date:** [July 18, 2003, 7:38pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/13 "2003-07-18T19:38:49Z")
I used to give all the time with no ill effects. About ten years ago, I became very ill with a nasty virus. Once I recovered and was able to give blood again, I became very faint and nearly passed out. About a year later I found out I had a slight heart murmur, which may have been caused by the virus. I haven’t given blood since, and I’m not totally convinced that the small valve defect could have caused the fainting, but it might be something to look for. ---
**Author:** ![amarinth](https://avatars.discourse-cdn.com/v4/letter/a/3be4f8/32.png) [@amarinth](https://boards.straightdope.com/u/amarinth)\ **Post date:** [July 18, 2003, 7:41pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/14 "2003-07-18T19:41:37Z")
Hmmm… I have medium blood pressure (100-110/70-80ish) but I fill bags fast. I also have great veins. (I just gave blood again! I’m so happy, my iron is usually too low!) I also usually just pop up off the table with no problems. Except once, the second time I gave blood, when about two hours later, I had to stand for a while, and all of the sudden, my vision just began to go brown from the sides. It got smaller and smaller (tunnel vision, I guess) and I felt faint, woozy, the works. I had to sit for the next while - way past the point where it was convenient. Ever since then (two-something gallons later) it’s been fine. So just because it went bad once doesn’t mean it will ever again. ---
**Author:** ![Redsland](https://avatars.discourse-cdn.com/v4/letter/r/9de0a6/32.png) [@Redsland](https://boards.straightdope.com/u/Redsland)\ **Post date:** [July 18, 2003, 8:00pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/15 "2003-07-18T20:00:48Z")
> [@](#): > > \*Originally posted by JKB \* > \*\*Went to a blood drive earlier this week, and nearly fainted afterwards while everyone else was just fine. Why? I wasn’t nervous and blood/needles/medicinal stuff doesn’t bother me. In fact, I was chatting and joking around with the other doners as they disconnected the bag, feeling fine then suddenly, WHOOSH! Blackout time. My mouth/throat went dry and I was soaked in sweat too. (oh, the shame). Everyone else was fine. Do some people physically overreact to minor blood loss? I don’t get it. Why was I such a wimp? \*\* The same thing happens to me every time I donate. The last time, as usual, I basically forced them to call a code blue on me. As I was coming back around, they asked if I was okay. I replied, “Yeah, this always happens.” The technician who was piling wet towels on my bare stomach cocked an eyebrow to communicate that I was a moron for repeatedly subjecting myself to this harrowing experience and told me that if I let the staff know about my “problem” ahead of time, there are things they can do to prevent and/or minimize it. I’m not sure what it is they do, but there you go. 🙂 ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [July 19, 2003, 7:38pm UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/16 "2003-07-19T19:38:38Z")
Similarly to **Redsland** , the last time I donated to the Red Cross at work, they suggested that I not donate again. The passing out happens to me almost every time. A few weeks ago I was at my doctor’s office to fill a small ampule of blood. I passed out, and have no idea why. It’s completely “normal” for me, I suppose. If I cut myself and see blood, it’s no big deal. I can take injections and IV’s with no problem, so it’s not necessarily fear of needles. I do have tremendously hard-to-find veins, though. It usually takes quite a few pokes to get to the blood, and more than once they’ve had to rotate the nurses or medics. I supposed my reaction could be a simple stress reaction that gets worse and worse every time I give blood, based on past experiences. In any case, the doctor told me to remind the nurses in the future that I should lay down to donate. I’m _really_ glad to see I’m not the only one with this insane reaction. Suddenly I don’t feel so un-manly. 🙂 ---
**Author:** ![JKB](https://avatars.discourse-cdn.com/v4/letter/j/7feea3/32.png) [@JKB](https://boards.straightdope.com/u/JKB)\ **Post date:** [July 21, 2003, 2:49am UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/17 "2003-07-21T02:49:47Z")
> [@](#): > > \*Originally posted by Podkayne \* > \*\*I passed out once a looong time ago when I cut myself, too. It didn’t hurt a lot, and I wasn’t bothered by the sight of blood. I was just standing there, unconcerned, while someone put a bandaid on my finger, and then I said, “I feel kind of–” and keeled. Luckily I was standing in a crowded kitchen and about three people caught me before I hit the floor. Nothing like that has happened since, again, probably because I am now very careful, and if I get a deep cut, I _sit down_ immediately, even if I feel fine. > > I’m healthy as a horse, otherwise. Never had any trouble with anemia. Just not so good with the blood-letting. \*\* Come to think of it, that happened to me once too. I was (stupidly) trying to scrape coconut meat with a sharp knife when the tip sank into my hand. D’oh! I clamped down on it immediatly so I didn’t loose much blood, and it didn’t hurt much, but within a minute… (fade to black). Maybe there’s some primitive psychological reaction that gets triggered or something. However, in another brilliant kitchen moment, I accidently spilled boiling water on my wrist. :smack: That _did_ hurt and _did_ scare me, but no blackout. Go figure. ---
**Author:** ![Mr.Excellent](https://avatars.discourse-cdn.com/v4/letter/m/f19dbf/32.png) [@Mr.Excellent](https://boards.straightdope.com/u/Mr.Excellent)\ **Post date:** [July 21, 2003, 3:18am UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/18 "2003-07-21T03:18:01Z")
Just a minor point: if you gave blood, you are _not_ a wuss. Period. Kinda pointless to say here, but damnit, people need to be _encouraged_ to give blood - it’s one of the finest things a person can do, and for some, also one of the scariest. So, Mazel Tov! ---
**Author:** ![magog](https://avatars.discourse-cdn.com/v4/letter/m/fbc32d/32.png) [@magog](https://boards.straightdope.com/u/magog)\ **Post date:** [July 21, 2003, 3:35am UTC](https://boards.straightdope.com/t/why-did-i-black-out-when-giving-blood-when-everyone-else-was-fine/189391/19 "2003-07-21T03:35:26Z")
I pass out when I give blood, reguarly enough where I let them know and expect it. Low-ish blood pressure, and not squeamish at all.