Can’t you tell by the stethoscope?
I was on a flight decades ago where a woman was vomiting and became hysterical (maybe a panic attack or something?). I kept my nose in my book. The plane continued to its destination.
Wow-- that is VERY smart! 
Ignorance fought!
When traveling to places with questionable medical infrastructure, my wife and I will generally get a prescription for ciprofloxacin in advance and take it with us. I don’t think we’ve ever had to use it, but it’s a nice security blanket when you’re 2 days walk from civilization. Might not be a terrible idea for any long trip, since if you get a fever on a plane you can do a lot worse than “start a course of cipro and hope it was bacterial”.
My father hated those situations. He was a pediatrician, and hadn’t practiced emergency medicine in decades ( since Med school, probably). But, he always responded — hoping another doctor would get there first
It’s a plane ride, not 2 days’ walk from civilization. That means the person getting the fever is less than 24 hours from medical care.
Taking an antibiotic “just in case” is not sound medical advice.
I could almost understand if it if the person has a history of diverticulitis and is familiar with the symptoms.
I’ve been given antibiotics prior to diagnosis of a given set of symptoms several times by doctors because “we’re not sure what this is, but let’s try a broad-spectrum antibiotic just in case” is a defensible medical tactic. Cipro is pretty mild as these things go, so the downsides of taking it unnecessarily are pretty small. I’ve taken it for a few weeks as as an anti-malarial prophylactic. In the absence of an actual doctor to consult, I’ll take the cipro.
I was on a transatlantic flight once where a passenger fainted. That plane also continued to its destination uneventfully. (I’m not sure they could have done anything else, short of maybe diverting to Reykjavik or something.)
Or the first member of a WWII submarine crew to require an emergency appendectomy on a South Pacific patrol.
“Lipes used bent spoons for retractors and alcohol from torpedoes for sterilization in 1942 when he removed the appendix of sailor Darrel Dean Rector aboard the USS Seadragon, 120 feet below the surface of the South China Sea.”
As for obligations for physicians to assist on in-flight medical problems:
“United States healthcare providers traveling on registered U.S. airlines have no legal obligation to assist in the event of a medical emergency. Canada and the United Kingdom also do not require that a provider assist. However, providers may feel an ethical obligation to help. Australia and some countries in the European Union do impose a legal duty on physicians to act.”
I volunteered in one (thankfully) benign medical situation in-flight. I’m not sure the patient would have been comforted to know that a pathologist was there to help. 
This reminds me of a time, many years ago, when I was returning from Europe. When I boarded the KLM flight in Amsterdam I felt perfectly fine. Two hours in I began to feel a tickle in my throat and my nose started to run. By the time we landed in San Francisco I had a raging cold. Worst flight of my life.
Aren’t a lot of aircraft equipped with emergency slides ?
I started a thread several years ago on this subject. I was on a flight where multiple people began collapsing unconscious. They were asking repeatedly for any medically trained passengers to assist and even put some of us to work helping in the aisles. I was puzzled by the fact it happened to several at once and asked the Dope for theories about the cause. IIRC, the prevailing theory at the time was a mass-fainting issue.
I can’t find the particular thread any more, but I think it happened around 2010 to 2013. For some reason I’m coming up blank in my searches for this.
We were more than halfway to our destination (DFW to Portland) and the pilot’s got priority clearance and our descent was much faster than ordinary (the engines remained spooled up until just short of the airport). We were met by EMTs with multiple stretchers to carry away the fallen. Within a short time on the ground, all had recovered completely. I started the thread out of curiosity whether some malfunction on the plane could have caused it.
There’s also this, 2nd post down is yours (that link is to the first thread I posted).
Excellent! How did you search for those? I’m still learning my way around the new forum application (Discord?).
I used the search string, without quotes, “@pullin fainting” and the second thread popped right up, and the original one was linked in your post.
If you search for @[username}, discourse will look for threads where [username] posted to it.