Hugo Paul Friedrich Schulz (August 6, 1853 - July 13, 1932) was a German pharmacologist from Wesel, Rhenish Prussia. He studied medicine in the universities of Heidelberg and Bonn, where he did scientific work in the physiological institute of Eduard Friedrich Wilhelm Pflüger (1829-1910). In 1877 he earned his doctorate, and in 1883 was appointed professor of pharmacology at the University of Greifswald.
Schulz is known for his research of a phenomenon known as hormesis, which shows that toxins can have the opposite effect in small doses than in large doses. He proved this in his experiments with chemical compounds on yeast cells. From his research came the Arndt-Schulz rule, a law concerning dosages in toxicology; named along with Dr. Rudolf Arndt (1835-1900).
Schultz published several works in the field of pharmacology; his 1898 book Pharmakotherapie being the best known.