i was having some big problems with this and went to the doc for bad bad headaches after smoking turns out it was just low blood pressure not enough blood to the brain and these were horribale threw up every and stuff almost eachtime i got one but ive lost a bit of wait since then and thats helped dramatically also sit doown clsoe you eyes about 5 minutes stand up with them closed and open them into the light if you pass out you have bad blood pressure high or low but im high ranting on here on every post so lol