I had fallen twice in one year after quickly standing and both time they required ER visits and stitches. The last time it required 12 staples in my head plus I suffered a concussion. Have you seen a doctor about this? I was referred to a cardiologist to rule out heart problems. After ruling out any cardiac reasons he duplicated the conditions (drop in blood pressure when quickly going from reclining to standing) in his office. He observed that my blood pressure became "thready". I was diagnosed with orthostatic hypotension. His advice was to up my sodium intake for my hypotension, and always sit up a minute before standing. Before walking away he said to be sure there is no light-headedness. He also said that there is a medication called flurinef acetate that could be prescribed if it begins to occur more often. (I was familiar with the medication because I had a dog with Addison's Disease that required it twice a day.) Like you there is no pattern to this with me and it has actually been something that I have dealt with my entire life. Since the issue is a random occurring event it is very hard to pinpoint when or if it will happen. If you haven't already done so, consult with a your PCP and see if you need to be referred to a specialist. He/she can then advise you from there as to what the underlying cause is.

Yes, I DO know what you go through, with the low blood pressure. Does this occur when you've been standing in one spot (such as in the kitchen when you're cooking) for a while? Is it worse when you're in the heat and sun and when you're exerting? If so, you need to ask your dr. to order a Tilt Table Test. That can determine if you have Orthostatic Hypotension (OH) -- a drop in BP of more than 20 points when standing). If the test is positive, you need to consume more sodium (contrary to what most people are advised to do) and try to avoid standing for long periods or working or exercising out in the sun and heat. Sitting down will counteract the problem, so wherever I go, I'm always on the lookout for a place I can sit, especially if it's a situation where most people are standing, such as a wedding reception, party, etc. I take a 1000 mg sodium tablet (over the counter in the pharmacy) three times weekly. Compression stockings are sometimes recommended, but I didn't find that they did much good. Medication can be prescribed by the doctor IF (and it's a big IF) you don't also have supine hypertension (SH), where your BP goes up when you lie down (such as overnight). About half the people who have OH also have SH. You would NOT want to take the medication for low BP if you also have the SH. I used to be stressed out about all the "weird things" that were going on with me, but now that I've found out about the condition (Pure Autonomic Failure), I understand it and know the lifestyle measures to try to cope with it, so that I'm not really stressed any more. Write back if you'd like to hear more about my experiences and what I've learned. This is not a common thing, and even doctors don't know that much about it. Some medical people have never even heard of it. It used to be called the Bradbury/Eggleston Syndrome, and some medical people might've heard of that.