Quick Introduction
She asked to increase to 60 mg, but he refused. She didn't challenge him.
Let’s just analyse what has happened:
- your sister is suffering from acne
- the dosage of medication doesn’t alleviate the acne as much as she hoped they would
- she asks that the dosage is increased furthermore
- the dermatologist refuses
- she increases the dosage herself
This seems like there is a lot of miscommunication going on here:
- the dermatologist hasn’t understood how severe the problem is to her and didn't communicate clearly what the treatment and prognosis are
- your sister didn’t understand why the dermatologist didn’t want to increase the dosage
Some Theory
The Revised Illness Perception Questionnaire (IPQ-R) categorises patient's perception of an illness into 5 categories:
- Identity
- Cause
- Timeline
- Consequences
- Cure-Control
Moss-Morris, R., Weinman, J., Petrie, K. J., Horne, R., Cameron, L.D., & Buick, D. (2002). The Revised Illness Perception Questionnaire (IPQ-R). Psychology and Health. 17, 1-16.
It is a doctor's job to be aware of the patient's illness perception, but it is also good as a patient to be clear about one's perception.
I've just gone ahead and did that for your sister (from what I got of your description). I'm not saying that her perception of the illness is correct and that this is how the illness de-facto is, but that this is how your sister probably views her acne.

From what I understood from your post, your sister's perception clashes with her dermatologist's perception in three categories: Timeline, Consequences and Cure-Control.
A potential fix
The dermatologist needs to communicate more clearly
- why the dosage was not increased, and why an increased dosage is not an all-fix. (Cure-Control)
- the consequences (Is it really permanent skin-scarring? How to prevent it? What damage control can be done?) (Consequences)
- the timeline/prognosis: How long will the acne affect her? When will the symptoms get better? (Timeline)
Your sister can achieve this by telling the dermatologist her illness perception and asking the above questions.
Your sister should not blame the dermatologist for the miscommunication, the fault might be on both sides.
Your sister should also not leave before she understands why the dermatologist doesn't want her to take a higher dosage, and if she continues to go against the dermatologist's recommendations, should ask herself why she does it and if a change of dermatologists would be in order.
What you should ('nt) do
- Do accompany her to the appointment
- Do talk with her about what she wants to achieve with this appointment
- Don't go with her into the patient's room, just wait outside. This is not a fight between your sister and an evil dermatologist, this is just your sister needing to understand why the dermatologist doesn't want her to take more medication and the dermatologist needing to understand why your sister wants to take more medication. Your presence will hamper the communication between them, and you will not be able to do anything as you are neither patient nor doctor.