Kallenbach was the homeopathic physician of the bankers Grunelius and Co, William II Elector of Hesse, Moritz August von Bethmann Hollweg, Daniel Heinrich Mumm, Amschel Rothschild, and he was a colleague of Johann Taubes Ritter von Lebenswarth, and he took over his practice in Frankfurt in 1850.
Kallenbach was also a colleague of Friedrich Jakob Rummel,
C G Kellenbach practiced in Gorlitz, in Berlin, and from 1850 in Frankfurt, where he was eventually forced out by the Sanitory Board in 1853 due to the success of his ‘large practice’, and he then relocated to Bockenheim, ten minutes drive from Frankfurt. Such was the outcry of support for Kallenbach, the four allopathic doctors on the Sanitory Board were forced to concede and Kallenbach continued his practice. In the 1880s, Kallenbach was practicing in Utrecht,
In Utrecht in the 1880s, C G Kallenbach was practicing in a climate where homeopathy was so generally accepted, he was able to proclaim that homeopathy was part of general medicine and that the new generation of medical practitioners should be acquainted with all forms of therapy, and he also admitted that scientific proof of the similia principle was still lacking.
C G Kallenbach submitted many cases and articles to various homeopathic publications, including an article on Vaccination and a smallpox epidemic in 1858-9, when he successfully used the remedies vaccinin and variolin, and a case of uterine cancer he cured with kreosote.
F W O Kallenbach 1829 – 1917 MD Utrecht, the son of C G Kallenbach, practiced in Utrecht and then moved to Rotterdam at the request of the Rotterdam Society of the Champions of Homeopathy who guaranteed him an income of 2000 Dutch florins for his first year of practice. Within a year, he was joined by another German homeopath A J Gruber. These two Berlin doctors became licensed to practice in the Netherlands after they had taken a second medical degree at Utrecht.
F W O Kallenbach became a staunch fighter for homeopathy in the Netherlands.