He was a prominent member of the so-called "somatic school" of psychiatry in Germany.
In 1830 he was named a professor of physiology at the university, however in 1832, along with physician Johann Lukas Schönlein and surgeon Cajetan von Textor, he was removed from his post for political reasons.
He then worked as a court physician in Weißenburg, later performing similar duties in Straubing, Ansbach and finally in Erlangen, where in 1850 he became an honorary professor of forensic medicine.
[2] Friedreich is cited by multiple sources as having provided an especially early medical description of transsexuality.
[3][4][5] In particular, they note his 1829 work, Θήλεια νοῦσος; historisches Fragment, within the Magazin für philosophische, medizinische, und gerichtliche Seelenkunde (and its later 1830 republication as part of his Versuch einer Literärgeschichte der Pathologie und Therapie der psychischen Krankheiten).