Commodus further reduces the purity and silver weight in 196 to 74% and 2.22 grams respectively, being 108 to the Roman pound.

His reduction of the denarius during his rule is the largest since the empire's first devaluation during Nero's reign.

Whereas the reign of Marcus Aurelius had been marked by almost continuous warfare, that of Commodus is comparatively peaceful in the military sense but is marked by political strife and the increasingly arbitrary and capricious behavior of the emperor himself.

In the view of Dio Cassius, a contemporary observer, his accession marked the descent "from a kingdom of gold to one of rust and iron"—a famous comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the decline of the Roman Empire.

Despite his notoriety, and considering the importance of his reign, Commodus' years in power are not well chronicled.

The principal surviving literary sources are Dio Cassius (a contemporary and sometimes firsthand observer, but for this reign, only transmitted in fragments and abbreviations), Herodian, and the Historia Augusta (untrustworthy for its character as a work of literature rather than history, with elements of fiction embedded within its biographies; in the case of Commodus, it may well be embroidering upon what the author found in reasonably good contemporary sources).

Dissatisfaction with this state of affairs will lead to a series of conspiracies and attempted coups, which in turn eventually provoke Commodus to take charge of affairs, which he does in an increasingly dictatorial manner.

Nevertheless, though the senatorial order will come to hate and fear him, the evidence suggests that he remains popular with the army and the common people for much of his reign, not least because of his lavish shows of largesse (recorded on his coinage) and because he stages and takes part in spectacular gladiatorial combats.

One of the ways he pays for his donatives and mass entertainments is to tax the senatorial order, and on many inscriptions, the traditional order of the two nominal powers of the state, the Senate and People (Senatus Populusque Romanus) is provocatively reversed (Populus Senatusque...).