I need to know the causes of a sudden drop in blood pressure.?

There can be many reasons

The first is the most common and is called vasovagal syncope, this is when a nerve called the vagus nerve gets stimulated for any reason (for example: the sight of blood, fear etc.) The vagus nerve is resoponsible for lowering the heart rate so when it is stimulated, your heart rate drops dramatically causing you to faint. If you notice the same stimuli cause you to faint, whatever it may be, this is probably the best explanantion.

Also, it can be because your blood vessels do not constrict enough if the amount of blood going to your head is down. In a healthy person, the blood vessels would vasoconstrict (tighten) increase the blood pressure if you suddenly stand up for example, but you may have a delayed reaction, causing a low amount of blood to reach your brain, causing you to faint. Your GP can give you whats called a tilt table test to see if this is the case. You say you faint while standing up, this is because the force of gravity draws blood from your head and the blood pools in your legs. In order to overcome this, you shouldn't lock your knee's whilst standing (ie. bend them slightly). This ensures the muscles are active so enough blood gets pumped out of your legs to be sent to your brain again. If you suddenly feel faint, sit down and put your head down to the floor so blood can get to your head.

You could be suffering from slightley irregular heart beats. When your heart is beating in regular patterns, the heart first fills with blood and then it sends a jet of blood off to the rest of the body. In some people, one heartbeat can occasionally beat too soon, and as a result, it is pumping on nothing as the heart hasn't filled with blood yet. This one misfire is enough to cause you to faint because of the temporary loss of blood to your brain, however the episode is quickly over as the next surge of blood comes a few seconds later. If you find that these episodes are very short, then this usually shows you have a heart problem.

These are the three main explanations for fainting, I hope it gave you an insight!

3 years ago, I was diagnosed - hypertension with a reading of 160/100. I used to feel dizzy a lot, my legs had awful cramps, and levels were very low in my potassium, causing my fingers and toes to always cramp together. One day I started to feel really faint while I was driving with my daughter in the back seat and I passed out, hitting 3 cars and ending up in a ditch. That moment,I knew I had to do something because my meds weren't working. I heard about this diet from a friend and thought I'd give it a shot. The results have been remarkable. In just 21 days, I honestly can't remember feeling this good, my blood pressure went from 175/110 to 125/70.

except you're in chf from an underlying illness that's inflicting low blood stress leap up and down and shout for exhilaration. you will stay an prolonged extra healthy existence than somebody with high blood pressure.

You need to get yourself checked out. There could be may reasons why this is happening.

Lack of eating?

speak to your GP

Death