Probably not a good sign.

[I'm-moving-on]

Whenever I stand up, I get really dizzy and my vision messes up temporarily. Lately, it makes me have to sit down. A year ago, it happened and I passed out once. Any ideas what it could possibly be?

[kadyCHAOS]

hey, sometimes I get this too, from the change in my blood pressure if I stand up from sitting too quickly. Maybe it has something to do with that?

[Incompris]

It's not that uncommon. I've passed out multiple times from it and once had a seizure from it. The blood is literally draining from your head to quickly. When it happens sit down immediately until the feeling subsides, you can get seriously hurt if you pass out and fall wrong.

After drink a Gatorade or something filled with sugar and calories. That will help. I've never fully understood it but somehow it's connected to being underweight, blood sugar, or being dehydrated/famished. That's all I remember the doctor saying.

[ThornedRose]

I'm anemic, which can be very common in girls, and have that same issue. Although, I have also heard that standing up too quickly and getting lightheaded is an actual illness, not deadly by any means, but I have heard of it.

[I'm-moving-on]

I know I'm not anemic. I was tested for that a few months ago when I had a surgery. It could be an actual illness.

[ThornedRose]

http://www.emedicinehealth.com/dizziness/article_em.htm

Read the second bullet underneath reasons one might be dizzy. Try not to worry yourself over it, but if it persists or gets worse maybe go to the doctor, but to me it seems harmless.

[I'm-moving-on]

Oh my. I might have to do that.

[escape_thereal_world]

If you are concerned, I suggest a doctor. Especially if you passed out from this before. It is common to feel dizzy after standing for a variety of reasons. Try standing up slower.

But only a doctor can tell you exactly why. Also, if it's persistent, then you should see a doctor anyway. This is common, but not usually consistently.

Hopefully that article Sydney linked you to will be helpful Good luck!

[Dream]

It could be several things. It could be blood pressure, although you would probably experience ringing in your ears or other symptoms if it is that. It could be blood sugar; your body might be having trouble regulating blood sugar and it could get too low. Another possibility is that you're anemic, meaning you don't have enough iron. There are others as well, but those are the three most common.