It works very well on me. Since I have rarely headaches, and if yes, there is always a good reason for them. Usually either big hangover, or exhaustion from lon

It works very well on me. Since I have rarely headaches, and if yes, there is always a good reason for them. Usually either big hangover, or exhaustion from long and intense effort in mountains, ie climbing Matterhorn 6 hours straight no stops, or similar effort on Mont Blanc that took 11 hours, both coupled with drinking too little/sweating too much -> dehydratation. Just drinking plenty afterwards doesn't remove headache, just makes it a bit less intense. I pop the pill, and in 20 mins it's over. Maybe if causes for your headache are different, the effect might not be so quick & effective.