Generic Cafergot is used for preventing and treating certain kinds of headaches (eg, migraines, migraine variants, "histaminic cephalalgia"). It works by constricting blood vessels in the lining of the brain, which helps to decrease the pain from migraine headaches. More info »
Regarding the effect: I do notice an increase in bloodflow and a better
stamina using the pills (I use 50mg). A side-effect I have noticed is that
my nose clogs up so I seem like I have a cold for an hour or so after taking
one pill. No other side-effects than that.