Viagra is a vasodilator, should not make your BP go up - or do you mean your pulse feels like it's pounding, perhaps beating faster to make up for the lower BP? That happens to me on occasion, but for other reasons (mild dehydration is one cause, lowers blood volume) - pulse gets really fast in response to an abnormally low BP, which for me means 90/60 or lower. Of course getting a headache due to taking an ED med is a pretty undesirable outcome all by itself - could you imagine taking one then having to tell the wife "not tonite honey, I have a headache"? LOL.