Monday, July 20, 2020

How quickly does poison take effect?

Old-school games tend to have a lot of save or die poisons– or save or lose CON, or save or fall asleep, and so on.  And they almost never specify how fast those poisons work.

That leaves an important question unanswered: if you get poisoned, how long do you have to cure it before you die?

That depends on two things: how fast the poison is absorbed into your bloodstream, and how quickly its effects manifest after that.  The second factor depends on the individual poison, so I'll focus on the first here.

There's also a distinction between when poisons first have a noticeable effect at all versus when their effects peak before starting to subside.  Again though, that's mostly down to the characteristics of the individual poison.  

Poisons mostly get into the body by three routes: inhalation, injection and ingestion.

Inhalation: Seconds to Minutes

This is generally the fastest route.  An inhaled drug gets into your bloodstream within seconds.  

In fact, if the drug/poison in question mainly affects the brain, inhalation is actually faster than injection.  How can that be, you ask?  It has to do with how the circulatory system is laid out.

So blood takes around 45-60 seconds on average to circulate through the body, then it gets back to the heart.  It goes through one side of the heart, then to the lungs to pick up oxygen, then through the other side of the heart, then up through the aorta and into the brain before circulating through the rest of the body.

In other words, a drug that comes in through the lungs actually gets to the brain faster than one that's injected intravenously.

Inhaled drugs and poisons reach the brain within 5-10 seconds, and reach peak concentration and spread throughout the body within a minute or so.  Death takes longer,  but often not much longer; sarin gas can kill in one to ten minutes.

There's very little you can do about inhaled poisons, unless the poison itself takes a long time to work even after absorption.  For balance purposes, they should probably do damage or permanent CON reductions rather than be save or die.  Historically this is pretty accurate; really lethal gas weapons didn't come into use until the 20th century, and even today they usually wound rather than killing provided they have room to disperse, albeit the wounds are often permanent.   

Injection: Minutes to Hours

In an OSR context, injection doesn't usually mean intravenously, like heroin.  Mostly it means poisoned daggers, fangs and the like, which will inject poison into fat and muscle tissue as well as possibly somewhat into a severed blood vessel.  That's slower than injecting directly into a vein, and the speed is a little inconsistent depending on what part of the body the venom goes into and how much blood flow there is. 

Real life snake venom offers a good guidelines here.  The fastest and deadliest snake venom comes from the black mamba, and it takes 20 minutes to kill an adult human.

Untreated rattlesnake bites usually kill within 6 to 48 hours, and almost never in under 2 hours.  It takes around a half hour before symptoms get really bad.

As a side note, around 20% of rattlesnake bites don't inject venom at all; rattlesnakes can't eat humans so they sometimes give us a warning bite and save their venom for actual prey.  Something to consider when running poisonous animals.

Bear in mind that humans are much bigger than the prey snakes usually eat; a bigger venomous animal could inject more venom and kill more quickly.

Contrary to popular belief, sucking the venom out does very little good.

A few drugs and poisons are absorbed transdermally– through the skin.  This works at around the same speed as an intramuscular or subcutaneous injection.

Ingestion: Minutes to Hours for Liquids, Hours to Days for Solids

Ingestion is extremely variable.  Alcohol hits you within minutes, but can take up to a half hour to reach peak blood levels.  Many encapsulated drugs take well over an hour to be absorbed, and sometimes several hours to feel the full effect.

In general, liquids will absorb a lot faster than solids.

Of course it also depends on how full your stomach is, as any experienced drinker knows.  A full stomach will slow down absorption and spread the effect out over a longer period of time, although the same amount of the drug will ultimately be absorbed.

Absorption is also more gradual; there can be a big gap between when you first feel sick from the poison, and when you absorb enough to actually die from it.  Ingestion gives you a lot of time to react.

It takes 1-3 days for food to completely transit through the digestive tract, but usually 36-48 hours.  It takes 3-5 hours to get through the stomach and into the intestine; before that point you'd need to throw up, afterwards it's too late to throw up but laxatives might help you.

Different nutrients and drugs are absorbed at different stages of digestions.  Most nutrients are absorbed in the small intestine, meaning a few hours after eating.  A lot of drugs can be absorbed through the stomach though, which means they can take effect faster.

There also tends to be a limit to how much you can kill people harder and faster by using a higher dose.  Most poisons taste bad– this is why we evolved to dislike very bitter flavors– so a higher dose will be more noticeable.  A higher dose will also make it more likely that the victim will reflexively throw up, so ingested poisons need to hit a sweet spot of lethal, but not enough to guarantee vomiting.  This is difficult. 

Also note that some "ingested" drugs are actually transdermal, absorbing through the skin of the mouth and throat.  Cyanide capsules are like this, which is why they can kill within minutes.

Antidotes and Antivenoms

All of this applies equally well to antidotes and antivenoms, which is why snake antivenom is injected rather than swallowed: you're in a race with the poison.

An ingested antidote probably won't help against inhaled poison.  A liquid antidote could help against a snake bite, but it would be less than ideal.  It wouldn't take effect until well after the venom, so it might save your life but be to late to prevent a large amount of tissue necrosis.  The calculus is presumably similar for injected antidotes versus inhaled poisons.

Most RPG settings don't have drug needles, but an herbal poultice rubbed into a wound should be absorbed at about the same speed as snake venom or poison from a dagger.

Magical cures are obviously ideal here, since they can work instantaneously, or close enough.  In fact magic might be the only good solution for inhaled poisons.   

Most settings also won't have inhalers, although incense does exist and antidotes could maybe be burned.  In fact now that I think about it, there's an argument to be made for rolling antidotes into little cigarettes and keeping them ready for use, assuming the antidote wouldn't be rendered inert by heat.  Food for thought anyway.    

1 comment:

  1. Bravo! A lot of the RPG poison have well, no bearing with reality. Route and dose matter so much.

    ReplyDelete