Usually it will not go away the whole day. Only in the evening that it starts to subside. And when I decide to take it, I need to do it in a specific way. E.g. direct lying extremely comfortably, but not sleeping, or it won't be as effective. Or drinking coffee in front of my pc. And a few other ones. I don't get why but I usually just feel what specific 'ritual' works best for any given moment. Sometimes I guess wrong and the headache won't disappear. This combination with coffee and adhd med seems to work best though.