I got Drysol through my dr. (in the US). I remember you had to apply the stuff at night and were supposed to put plastic under your arms to maximize the effect - I didn't do this but it still worked on me. It itches when you apply it (for like a couple of hours) but you can't put lotion on top of it - I used the lotion the day after which helped with the dryness of the area.

For me, it seriously itches when its soaking in but I tend to have sensitive skin so maybe that was just my experience. It is totally worth it if you oversweat.