I was miserable. I took it at 4:30 AM - nothing. I sat around suffering until someone told me to take some SM tea. I did that about 1:00, but didn't feel any relief until 6PM that night. The salt really backed me up for some reason.
This is just me, and how it effects my body -- we're all different.
I'll give you the same advice that was given to me -- have some tea and that should make you feel better.