The surgical treatment of glottic insufficiency due to lesions of the recurrent laryngeal nerve has become a routine procedure in the last few decades. In particular, injection laryngoplasty with polydimethylsiloxane (PDMS) has proved to be an easy, effective and safe method for vocal fold medialization. It is a biologically inert substance having almost ideal properties as a filler; complications related to its intralaryngeal use such as migration, or granuloma formation are extremely rare and allergic reactions have not been reported as yet. We discuss two cases representing the first description of acute severe complications after injection laryngoplasty with PDMS.