Does swallowing dust, cotton, or makeup powder that goes down from the nose to the throat invalidate the prayer?

The treatment for obsessive thoughts is to fight them off and not succumb to them, for succumbing leads to great evil. You must continue to resist them until Allah removes them. Prayer is not invalidated by swallowing saliva or similar substances, nor even by swallowing food particles stuck between the teeth, because it is impossible to guard against such things.