Humboldt University of Berlin.
From 1865 to 1868 he was an assistant to Ernst Viktor von Leyden (1832–1910) at the University of Königsberg where, in 1866, he was habilitated for internal medicine. From 1868 to 1870 he worked as a military physician and lecturer in Berlin and later served in the same roles at Breslau (1870-1872). In 1872 he relocated to Freiburg and in 1874 was appointed full professor at the medical clinic in Jena.
From 1882 until his death in 1905, he was a professor at the university clinic in Vienna.
One of his better known students was Constantin von Economo (1876–1931). In 1876 he described the irregular pulse associated with atrial fibrillation.
At the time he referred to this finding as "delirium cordis". The eponymous "Nothnagel"s syndrome" is named after him, a disorder characterized by ipsilateral oculomotor palsy and contralateral cerebellar ataxia.
He died in Vienna. In 1922 medical historian Max Neuburger published his biography with the title "Hermann Nothnagel, Leben und Wirken eines deutschen Klinikers".
German Academy of Sciences Leopoldina]
In 1879 he became a member of the Deutsche Akademie der Naturforscher Leopoldina.