In 1864 he received his medical degree from the University of Heidelberg, where for several years he served as an assistant to pathologist Nikolaus Friedreich (1825–1882).

[1] Erb began his medical career in the fields of toxicology and histology, but later his interest switched to neurology, of which he became one of the 19th century's leading neurologists.

In 1878, he described myasthenia gravis, a condition sometimes referred to as the "Erb-Goldflam disease" (named along with neurologist Samuel Goldflam).

He was the author of over 250 medical works, including Handbuch der Elektrotherapie (a textbook on electrotherapy), and an important study on spinal paralysis.

In 1891, he contributed to the foundation of the journal, Deutsche Zeitschrift für Nervenheilkunde – in its first volume, he published a survey on muscular dystrophies.