In a professional context, health care practitioners of any kind holding state licenses for diagnosis and treatment in independent practice are customarily addressed as doctor, whether they are M.D., D.O, OD, DDS, DMD, DC or PsyD, DPM,. Like it or not, this is the custom most professions adhere to and most patients seem to ready to adopt.
I'm a clinical psychologist. I don't introduce myself as Dr. XXXXX, but in every clinical setting I've worked, including hospitals, staff, including MDs, have formally introduced me and addressed me as Dr XXXXXX in meetings or if we don't work together regularly. Even though I always introduce myself by first and last name to new patients in a practice setting, many patients persistently refer to me as Dr. XXXXXX.
The answer to the question of when to use the title can't be found in a rule book. We can only look at what is customary. It is unethical to mislead patients about one's credentials. If I have an inkling that someone believes I'm an MD, I clarify for them. And sometimes people ask for clarification on their own. Confusion can arise because of significantly overlapping scope of practice for psychiatrists (MD or DO) and clinical psychologists (PhD or PsyD.). Often we work in the same setting, treat the same disorders and even hold appointments on the same faculty. It's not uncommon for patients to see both a psychiatrist and a psychologist for treatment. I think the confusion is less likely to arise in other areas of professional practice (e.g. dentistry, chiropractic, veterinary medicine) because scope of practice overlaps with MD/DO practice very little to not at all.
What differentiate pharmacists from all the above professions is that pharmacists are not licensed to diagnose or treat anything. They are licensed to dispense medication ordered by physicians. On that basis, the use of the title "doctor" would not be customary, except perhaps if they are working in a university setting. But it's a little fuzzy with PharmDs because they do work in health care and they hold a license. Personally, I couldn't care less if they want to use the title as long as they never do so in a misleading manner and never misrepresent their professional competencies. They've gone through a doctoral programs and, and though not customary, it doesn't seem outrageous to use the title within a professional context. I would imagine that like people in my profession, they are not inclined to misrepresent themselves.
