Medicaster

But these innovating Medicaſters have introduced a Practice not only very precarious, but in many Reſpects extremely dangerous, and quite devoid of any one of the Qualities which conſtitute a good Remedy, viz. to cure the Patient, as the Axiom has it, cito, tuto, & jucunde, i.e. ſpeedily, ſafely, and pleaſantly.

Source: wiktionary

The most idiotic medicaster, when he had named, or, as they term it, diagnosticated a typhoid fever, found himself upon a level with the medical celebrities of the epoch. […] If the patient died, that was perfectly simple: he had a typhoid fever to which he was inevitably doomed to succumb! If he recovered, what a noble triumph for the medicaster, even when he had perhaps arbitrarily imposed the name of typhoid upon a simple and benignant fever, as is constantly done!

Source: wiktionary

[I]t [opium] is a double-edged sword, a divine gift in the hands of a master, a poison in those of a mere routinist—a medicaster—a demi-physician.

Source: wiktionary

[I]f pushed, I would judge that many of those ‘medicasters’ and ‘charlatans’ commonly arraigned as tricksters were less cheats than zealots: if we are to speak of delusion, it is primarily self-delusion[…].

Source: wiktionary