Brehmer was born in Kurtsch (Kurczów) near Strehlen (Strzelin), Prussian Silesia.
[1] Alternately, as a botany student in Silesia, Brehmer was diagnosed with tuberculosis and told to find a healthier climate.
In 1854 he returned to Germany to study medicine, ultimately writing a dissertation titled "Tuberculosis is a Curable Disease".
[2] By 1854 Brehmer had settled in Görbersdorf (Sokołowsko), Silesia and opened the Brehmersche Heilanstalt für Lungenkranke, a hospital in Görbersdorf where patients were exposed to plentiful amounts of high altitude fresh air, and good nutrition.
Brehmer and Dettweiler's work was the primary influence on Dr. Edward Trudeau in establishing the successful Adirondack Cottage Sanitarium at Saranac Lake, New York, in the 1880s.