The Collaborative International Dictionary of English v.0.48:

Rubefacient \Ru`be*fa"cient\, a. [L. rubefaciens, p. pr. of
   rubefacere to make red; rubere to be red + facere to make.]
   Making red. -- n. (Med.) An external application which
   produces redness of the skin.
   [1913 Webster]

WordNet (r) 3.0 (2006):

rubefacient
    n 1: a medicine for external application that produces redness
         of the skin