Why do i get loss of vision and dizziness when i stand up?

Okay, this is hard to explain. When I stand up, my vision will start to blacken from the outside, and then make its way to the center. While this is happening, I get very light-headed. My bloodpresure is not normaly low either. When this happens, I have to hold on to somthing or i'll lose my balence. I am 14 years old, and im in good health. The one worst case of this happend when i was at a museum. My head started pounding, i lost all of my vision, and i was about to fall down. (luckly my grandfather caught me and led me to a chair). i really want to know if there is somthing wrong with me. Any advise would be great.

Thanks,
Michael

This is something that I find very common. It happens to me a lot and I really don't worry. If it happens a lot its probably due to the rush of blood out of your head when you stand up quickly. That is what the doctor has told me. So unless it becomes a constant thing and it is debilitating, I wouldn't worry

No, it's normal. That's happened to me after I've been reading for a while, and I'm 12. You're fine. I don't fall down, and it clears up in about 3 seconds, but I know what it is.

Your fine don't worry. The problem is you stand up to fast take your time getting up. Don't just jump right up.

Nothing to worry about here, it happens to everyone. Some people experience more severe symptoms than others, but when you stand up especially quickly it's not at all uncommon to become lightheaded or dizzy.
Even losing vision isn't weird.

I don't have a medical explanation, and I'm no professional, but I can tell you that you shouldn't be too worried about this.

go 2 the doc and stop askin people on the web u sea doc could help u better than us

The people here saying not to worry are not correct. People that are perfectly healthy do not become dizzy upon standing from a seated or reclined position. It sounds like an equlibrium problem. My best suggestion is to tell Grandpa (or a parent) that you need to go to the doctor.

this is called postional hypotension. Are you standing up very quickly? if you are, the blood wants to stay where it is( objects at rest stay at rest, newton's laws, snore snore) and it deprives your brain of the oxygen it needs to work.
You can check this yourself. Get a blood pressure cuff and take your blood pressure sitting down and then again after you stand up quickly. The second will be lower.
Try getting up slower, but if this continues, go see a doctor.

i'm 18 and i have exerienced this several times, once it happened in the shower and i actually fell over and passed out... so it was not a caase of standing up too quickly. i am a female and sometimes i don't eat everything that i should including carbs. usually when i have been dieting i experience this the most. so make sure your eating a balanced diet and it may prevent these episodes.