Disclosed is an inflatable balloon for medical use, intended to be inserted deflated into a human or animal body cavity and then inflated once inside this cavity so as to apply pressure against the cavity. The inflatable balloon includes a balloon body, the wall of which is made from a flexible inflatable material, the balloon body having a generally elongated shape with a proximal inflation end and a distal positioning end at the back of the cavity. It further includes an inflation opening formed in the proximal end through which a fluid is introduced into the balloon body so as to inflate it under pressure. The wall of the balloon body locally has an elongated portion called the sole that is stiffer than the rest of the wall, this sole extending from the proximal end to the distal end.