As stated above, I think we can clearly state that personal medical questions of any nature are off topic and liability.
The line that I think should be drawn, is whether or not the question is asking for a preferred course of treatment or likely prognosis.
[Course of treatment; C]
A person has X, Y, Z symptoms (or known disease), what would be the
best treatment for this person? =>Not allowed.
A person has X, Y, Z symptoms (or known disease), would treatment A
or B be more appropriate and why? =>Not allowed.
A person has X, Y, Z symptoms (or known disease), why does the human
body/disease/pathogen produce symptom X/Y/Z? =>Allowed. The lead in
person with X/Y/Z symptoms is erroneous and should be edited out,
but the question "Why does the human body produce symptom X" is of a
biologically relevant mechanism question. Specific example: "Why
does the body sometimes respond to infection with a fever?" or "Why
do bacterial infections often induce fevers?"
What causes X symptom from R disease/pathogen? =>Allowed, same as
Why is treatment A used for R disease/pathogen? =>Allowed. Again
driving at the underlying biology/pharmacology/bio-chem mechanisms
in play. "How does treatment A interact with disease/pathogen R,"
would be another acceptable rephrasing.
How do treatments A and B differ in how they interact with
disease/pathogen R? =>Allowed, same as above.
How do treatments A, B, and C effect the body? =>Possibly allowed
with editing and clarification. We don't want to get into what
possible symptoms could be, and any desire to list symptoms should
be prohibited. However, I think different underlying
immunological/pharmacological differences could be on topic. For
example, you could get into the difference in the immune response to
live attenuated vaccines vs heat-inactivated vaccines. Also want to
look out for generally low quality questions in this section.
I'm taking a course in [medical field] and was told X, but why isn't Y? => Rarely
allowed because I don't think these are likely to yield meaningful biological
discussion, have a very low scope of relevance, and tend to be poor questions in
A person has symptom X, what is going to happen to him/her? Not
A person has disease R, what is going to happen to him/her? Not
Would doing X make a person sick? or What would happen if a person
did X? =>Not allowed, and probably a poor question.
A person has disease/pathogen R, what will happen if they undergo
treatment A/B/C? =>Not allowed
A person has disease/pathogen R, what will happen if they don't
undergo treatment? =>Not allowed.
Why does disease/pathogen R often cause X? Allowed. I think this
again can get at the mechanism. Some specific examples: "Why does
Ebola often lead to death?" or "Why does obesity often lead to
diabetes?" We have to careful that these questions don't get too
I think the good rule of thumb would a "mechanism" test:
Can this question be properly answered in terms of the underlying biological mechanisms of [medical issue]?
If the answer to that is yes, then I think the question is probably on topic. If not then it probably isn't. I think it is easier to conceptualize how mechanisms are relevant in certain medical fields (ie pharmacology). But I don't think this precludes mechanistic questions on less obvious fields like surgery.
This had me reviewing one of my first answers, which I'm beginning to feel is off topic as it sits. I think that I could go into the mechanisms of arterial retraction, blood loss effects, or physiological responses to hemorrhage, but that is not what the question asked. Instead I think it might be an example of C1 (categorizing the examples above under C or P), which should not be allowed. The question could be pushed into C5, but is not currently phrased as such. I must admit that this personally makes me sad as I had liked my attempt at bringing the subject to the public.
I also want to point out that I don't think we should limit ourselves to human medicine. If any of the above questions had been asked in veterinary setting I think they would also be off topic ("a person" replaced with "a dog"). I get a little less clear on "lower" species or plants. I'm inclined to apply the same rules as above. If someone wants to ask about the prognosis of a plant virus, then I'm inclined not to answer. If someone wanted know how some insult caused X symptom in plants, then I think it would be on topic to address.
I also think there needs to be some clear thought on how medical questions are tagged. Should they be tagged as medical? I think broken down into specific fields is a good idea (pharmacology, infectious diseases, oncology, etc), but I don't know if they should get an additional medical tag? That might at least help us track how these questions are trending and their closure rate.
Lastly, as previously discussed, I think that most medical-class related questions are going to be poor questions.
First, I must admit that my participation in the community has been intermittent/punctuated. Also, if you've guessed from a few of my answers, I'm coming from the medicine side of things, though with a clear focus and experience in biological research. More specifically I've been working in Infectious Diseases for last 10 years or so.