In “Romeo and Juliet” Juliet takes a drug to mimic death. This seems to be a fairly common plot point where there is some drug which even if the person is examined by a doctor they can still be seen as dead even though some life stays in them. Are there any drugs that slow down the body to such a degree that it would prove near impossible to tell the difference? Any that you could recover from without danger?
Disclaimer: I am NOT a doctor.
My personal guess is that in the time period the story was set, medical knowledge was not as advanced as it is. And there were probably “folk healers” who knew more about certain herbs and such than “doctors” (or whatever).
It might be just like back in the day, midwives were more skilled in assisting in childbirth as doctors were. Once again, this is an educated guess.
A quick Google (see for instance BBC and Royal Society of Chemistry on drugs in Shakeapeare) indicates that many people believe Shakespeare intended for Juliet’s potion to be made from belladonna and/or mandrake, both of which were historically used as sedatives. Juliet alludes to mandrakes before drinking the potion.
The BBC piece cites a 16th century book of herbalism that says a “moderate amount” of belladonna can induce a “dead sleepe”, although this presumably means a deep sleep – the BBC notes that it would not produce a coma that could be mistaken for death. Both belladonna and mandrake can produce actual death though, so don’t try this at home.
One test of life that was apparently actually used was to see if a person’s breath fogged up a piece of glass. A person who is unconscious but in some distress will usually breathe through the mouth, and that will cause a piece of glass to fog. Someone drugged into a very deep sleep will be breathing shallowly, and through the nose, most likely, and not fog up glass. If you are drugged from something like belladonna (aka, deadly nightshade), your pulse may be slow and faint, so that a lay person my not find it, albeit, I’m not sure how much people in Shakespeare’s time knew about finding pulses.
I’m not just thinking Shakespeare’s time. Is there a drug we have today that could actually fool a doctor?
Not for amateurs. There is a fine line between dead and almost dead. That is why we pay anaesthetists the big bucks, and why there is one in every single surgical operation. Their job is to constantly monitor things like vitals and levels of consciousness. Drugs with an effect so profound as to mimic death do not work in the way you seem to think. These things are not like panadol, where a dose can be satisfactory within a wide range, and have very reliable consequences over a predictable period of time. You have to pay extremely close attention. Or people just die for real.
The idea of a death-mimicking drug that is not actually insanely dangerous is as fictional as the idea that you can hit someone on the head with exactly the right amount of force to knock them out for exactly the time you need them to be out for. Reality refuses to co-operate with the need for fictional tropes.
Yeah, remember Juliet wakes from her coma like waking up from a nap. Totally fictional device.
Even today, this is accepted in fiction. There was an episode of House where House woke up a guy from a twenty year coma, and the guy was walking around in minutes perfectly fine. No muscle deterioration, no brain damage, nothing. I never understood the appeal of that show with all the bullshit it had, but other people accepted it and loved it.
I’m not sure it could–not in the modern day, unless you were in the realm of sci-fi or fantasy anyway. I’ve always been fascinated with this sort of thing as a device, but if I ever used it in a story it would have to take place in the 19th century at the very latest. I don’t know if such a thing could work today with the equipment and techniques used to ascertain vital signs. In Shakespeare’s time and in other past times, as a poster upthread mentioned, the most they could do was hold a mirror up or listen to the chest (and presumably, such a drug/potion might slow down the heartbeat).
Of course, there’s always the possibility that the potion was the Draught of Living Death… 
(My HP headcanon was that Shakespeare himself was not a wizard, but was close friends with one…Christopher Marlowe. It was from Marlowe that he got details such as the Draught for Romeo and Juliet, and various touches in Macbeth and The Tempest. Marlowe himself wrote Doctor Faustus as a satire on how Muggles see wizards, and faked his death in that tavern brawl to be able to continue his work as a wizard undetected, perhaps in collaboration with John Dee.)
Tetrodotoxin is the current trope toxin of choice.
Of course, it doesn’t actually work like that …
Not as completely off-the-wall as you might think:
Link to full article. Google search link with actual medical journal articles.
TV / movies need to be entertaining, so the truth gets embellished and / or things get glossed over to fit the show into the time allotted. House usually covered real (though rare) conditions. What I found most unrealistic about it was the percentage of successful diagnoses - even if you go to a real-life doctor specializing in diagnosing unusual conditions (like the Mayo Clinic), whether or not they can provide a workable diagnosis / treatment plan is still pretty much random. I have a friend who has a bizarre condition, to the extent that one specialist commented that if they identified her condition, it would probably be named for her (or the doctor that found it).
I knew a doctor who liked it. First he accepted that it was complete bullshit, and that a competent physical examination at admission would have given the correct diagnosis in 99% of the cases. Then he enjoyed the soap opera and the clues.