Friedrich Ludwig Kreysig (7 July 1770 β 4 June 1839) was a German physician born in Eilenburg.
In 1795 he received his medical doctorate from the University of Leipzig, and during the following year served as a substitute to Johann Gottfried Leonhardi (1746β1823) at the University of Wittenberg.
In 1801 he became a professor of anatomy and botany at Wittenberg.In 1803 he was appointed personal physician to Frederick Augustus, and from 1815 served in Dresden as a trainer of Saxon military doctors.
Due to health reasons, he left academic work in 1822, retiring to a private practice, from which he concentrated on botanical studies.
Kreysig is largely known for his work with cardiological diseases.
In 1815 he explained inflammatory processes associated with endocarditis.
With physician Ernst Ludwig Heim (1747β1834), the "Heim-Kreysig sign" is named, which in adherent pericardium, an in-drawing of the intercostal space occurs, synchronous with the cardiac systole.In 1828, he was elected a foreign member of the Royal Swedish Academy of Sciences.
Kreysig died in Dresden.