Aretaeus left many fine descriptions of disease; in fact Garrison ranks him second only to Hippocrates in this respect. In the printed editions of this bibliography, before the present online version, the Adams edition was cited no less than 12 times for individual diseases, plus its first citation in "Collected Works" (No. 22.) This number of citations is, of course, greater than any other specific work by any other author, though the number of citations may be a reflection of idiosyncracies of the compilers rather than a proportionate measure of the significance of Aretaeus in the history of medicine. The citations are as follows:

3162. On angina, or quinsey. In his Extant works, ed. F. Adams, 249-52, 404-07.

3163. On pleurisy. In his Extant works, ed. F. Adams, 255-58, 410-16.

2433. On elephas, or elephantiasis. In his Extant works, ed. by F. Adams, 366-73, 494-98. Classic description of “elephantiasis Aretaei”, nodous leprosy.

5046. On ulcerations about the tonsils. In hiis Extant works, ed. F. Adams, 253-55. Aretaeus’s description of ulcerations about the tonsils, which he called “ulcera Syrica”, clearly referred to diphtheria, of which it was the first unmistakable description. For his treatment of the disease, see pp. 409-10 of the same work.

5089. On dysentery. In his Extant works, ed. F. Adams. 353-57. Prior to Lösch’s discovery of E. histolytica, all forms of dysentery were differentiated only on clinical grounds.

4915. Extant works. Ed. F. Adams. Aretaeus wrote important accounts of melancholy (298-300, 473-78) and madness (301-04).

5146. On tetanus. In his Extant works, ed. F. Adams,  246-49, 400-04. Aretaeus left a full account of tetanus.

4484,  On arthritis and sciatica. In his Extant works, ed. by F. Adams,  362-65, 492-93,

3612. On jaundice, or icterus. In his Extant works, ed F. Adams, 324-28.

4510. On paralysis. In his Extant works, ed. F. Adams.

4808. On epilepsy, in his Extant works, ed F. Adams,  243, 296, 399, 468. Aretaeus was well acquainted with hemi-epilepsy from local injury in the opposite half of the brain; partly from this knowledge he formulated the “decussation in the form of the letter X” of the motor path. He first described epilepsy resulting from a depressed fracture of the skull. In his excellent description he made the first mention of the aura.

3925. On diabetes.In his Extant works, ed. F. Adams. 338-40, 485-86. The first accurate account of diabetes, to which Aretaeus gave its present name; he insisted on the part which thirst plays in the symptomatology. 

According to the Wikipedia article on Headache, Aretaeus also provied the first recorded classification system for headaches: "He made a distinction between three different types of headache: i) cephalalgia, by which he indicates a shortlasting, mild headache; ii) cephalea, referring to a chronic type of headache; and iii) heterocrania, a paroxysmal headache on one side of the head." 

Digital facsimile of Adams's Greek and Latin edition from the Internet Archive at this link.