App is broken
Dragging the slider to set an intensity causes the app to switch tabs, so it is not actually possible to record a headache with an intensity other than the default 5.
Not enough ratings yet to assess One Tap Headache Diary.
One Tap Headache Diary appears legitimate, with a few gaps. AppsHunter Legitimacy Score for One Tap Headache Diary is 65/100.
Based on 65 of 100 points across 7 verification signals from App Store and developer data.