Here's another attempt at answering this question
Me: Propavan doesn't work for me anymore.
Psychiatrist: Of course it does, people don't build up a tolerance to Propavan.
Me: But I used to fall fast asleep from half a pill. Now I take two, and still lie awake all night.
Psychiatrist: No, that's not how Propavan works. You don't build up a tolerance to Propavan, they work just as well after many years as they did initially.
Very well put!
If there's no need to discuss epistemic injustice in particular, because we already have the broader concepts of good/bad clinical practice, why stop there? Let's ditch all that talk about Good Clinical Practice and stick to ETHICS! Since ethics covers all of human life, it also covers clinical encounters. We should just ask ourselves whether a clinician behaved ethically or unethically with their patients, no need for all these special concepts! (Sarcasm.)
On a possibly related note, from recent Swedish news: A patient in a psychiatric ward tells the staff that a squirrel got into their room. They have to "work hard" to convince the staff that this is really the case. After staff realizes that a panicking squirrel really is running around all over the place, they call the police (!) who explains that squirrels aren't their area. The police still puts them in touch with some wildlife center who managed to help them out.
Dr. Aftab is surely right that psychiatrists ought not take an antagonistic stance toward the concept of
epistemic justice. Equally, psychiatrists need to recognize that the patient's narratives and experiences should be heard and considered with open-minded respect and contextually-appropriate credence.
That said--as per my earlier comments in this forum [see "for context"], I am not sure that the construct of "epistemic justice" or "injustice" is conceptually or logically coherent; or that it is needed to carry out sensitive, empathic and clinically valid psychiatric treatment.
A good example is provided by Prof. Jeppsson and her experience with a psychiatrist who dismissed her report that "Propavan doesn't work for me anymore." Propovan [propiomazine] is a sedating antihistamine with a very complex receptor blocking profile , and is structurally related to promethazine and the phenothiazines. Tolerance to sedating antihistamines is well-known to experienced psychiatrists and sleep specialists; e.g., "Tolerance to sedating antihistamines can develop with long-term use, meaning higher doses are required to achieve sedation." 
So, the psychiatrist who insisted that, "You don't build up a tolerance to Propavan" was almost
certainly wrong on the pharmacological facts, and compounded the error by being obstinate and dismissive. Do we really need to invoke this highfalutin term--"epistemic justice"--to point out that psychiatrists ought to know whereof they speak, and should treat their patients' reports with respect and humility? Or is the term "epistemic justice" really an example of "talking on stilts"? By way of Occam's Razor, I have my misgivings!
Ronald W. Pies, MD