[1] Gallinger studied medicine at the Cincinnati Eclectic Medical Institute and graduated at the head of his class in May 1858.

[1] He was an active member of the American Institute of Homeopathy from 1868 to 1880, and throughout his political career, he was a forthright advocate of the homeopathic school of thought and practice.

Besides the AIH, he was a member of many state and national medical societies and a frequent contributor to the journals of his profession.

In 1888, Gallinger served as chairman of the New Hampshire delegation to the Republican National Convention at Chicago, where he seconded the nomination of Benjamin Harrison of Indiana for president.

[2] He was named a member of the National Forest Reservation Commission, established by the Weeks Act, which Gallinger sponsored in the Senate.

[3] Gallinger received the honorary degree of A.M. from Dartmouth College in 1885 and served as trustee of George Washington University for several years.