So, I'm looking to get one of my characters poisoned. However, if they notice that something's up, the jig's likely up as they'll seek treatment for what happened, so this needs to happen "under their radar" so to speak. Hence, the poison needs to have the following traits:

  • Delivered by ingestion (in food or drink) -- dosing can be a single dose, or multiple doses over the span of a couple of days provided symptoms do not start until after the dosing is complete.
  • No strong off taste, odor, or color (mild tastes/odors/colors can easily be disguised/masked by putting it in an appropriate preparation though)
  • Delayed action (hours to a few days after dosing is complete) so that they don't associate what's happening with their last meal/drink.
  • No gastrointestinal symptoms once the poison starts to take effect -- again, so they don't associate what's happening with their last meal or drink.
  • Complete effect of the poison (i.e. total incapacitation) needs to be within an hour, if not within the span of minutes, after symptoms start to manifest.
  • Needs to be incapacitating for a period of one week minimum, if not fatal.

Do any known poisons do this? In particular, I'm concerned about the "no gastrointestinal symptoms" part, as it seems that all the real-world poisons I've researched cause gastrointestinal disturbances when ingested.

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    $\begingroup$ Please, tell us you're not planning something in real life ^^ $\endgroup$
    – Tyrabel
    Commented Dec 27, 2015 at 19:44
  • $\begingroup$ @Tyrabel -- thankfully, no, I am not -- this is all aimed at a fictional character. The reason I'm asking for a real-life example is because a more straightforward reality-check would have trouble escaping "a plant did it" territory $\endgroup$
    – Shalvenay
    Commented Dec 27, 2015 at 19:49
  • $\begingroup$ I don't have any answers, but if you already checked the real-world plants and found quite what you want (ie. poisonshroom), you can either say it's a variety of poisonshroom without the disturbance, or it's poisonshroom with something else that can hide the disturbance. It doesn't have to be a single plant, right ? $\endgroup$
    – Tyrabel
    Commented Dec 27, 2015 at 20:01
  • 5
    $\begingroup$ No noticeable effect for hours or days, then total incapacitation within an hour is a very rare combination as you require a poison to be both slow-acting initially and then fast acting. Poisons encapsulated in a gelatin capsule that delays initial onset could work, but the victim would notice the capsules. $\endgroup$ Commented Dec 27, 2015 at 20:52
  • 1
    $\begingroup$ @GaryWalker Not necessarily. You can make capsules small enough that they get eaten unnoticed if you use a plastic that reacts with acid and heat. I mean, you don't care if the container has a chance of causing side effects and it is a single dose only, so you can use lots of stuff you can't normally use for food or medicine. $\endgroup$ Commented Dec 27, 2015 at 20:57

10 Answers 10



Famously used in Breaking Bad, I think this is probably the poison you're looking for.

Delivered by ingestion (in food or drink)

According to the Wikipedia page, A dose of purified ricin powder the size of a few grains of table salt can kill an adult human.

No strong off taste, odor, or color

If you put 3 grains of table salt on a burger, would you taste it?

Delayed action (hours to a few days after dosing is complete)

From the wiki page, Because the symptoms are caused by failure to make protein, they emerge only after a variable delay from a few hours to a full day after exposure.

No gastrointestinal symptoms once the poison starts to take effect

In the case of a non-fatal overdose, Victims often manifest nausea, diarrhea, fast heart rate, low blood pressure, and seizures persisting for up to a week. In the case of a fatal amount ingested, Ricin causes severe diarrhea, and victims can die of circulatory shock. Diarrhea can be caused by a number of things, such as food poisoning or unsanitary water, so while they may make the link to their last meal, they might not necessarily think it was poisoning.

Also of note, ricin is also poisonous when inhaled, so the victim need not ingest it to receive a lethal dose.

Complete effect of the poison (i.e. total incapacitation) needs to be within an hour, if not within the span of minutes, after symptoms start to manifest.

This one, I haven't been able to find information on. My guess is that if you're worried about the victim seeking treatment, it shouldn't be much of an issue - all cures currently in development seem to be experimental, and have not undergone human trials yet.

Needs to be incapacitating for a period of one week minimum, if not fatal.

Again according to the wiki, Death typically occurs within 3–5 days of exposure. For a non-fatal overdose, as stated above, symptoms typically last for up to a week.

You can find more info on Ricin here.

EDIT: Another possible poison is Strychnine... I'll try to put together a more thorough answer tomorrow.

Strychnine is a really interesting neurotoxin with some pretty brutal symptoms, but they typically occur within 15-60 minutes of ingestion (Source: CDC).

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    $\begingroup$ According to the CDC - Ingestion: If someone swallows a significant amount of ricin, he or she would develop vomiting and diarrhea that may become bloody. Severe dehydration may result, followed by low blood pressure. Other signs or symptoms may include hallucinations, seizures, and blood in the urine. Within several days, the person's liver, spleen, and kidneys might stop working, and the person could die. Definite gastro-intestinal symptoms for oral administration. $\endgroup$ Commented Dec 27, 2015 at 20:56
  • $\begingroup$ The trick is that it is also deadly if inhaled - you could probably put it in a cologne or body spray, if you weren't concerned with the poisoning of all people around the person you're trying to poison. However, that's pure speculation. That said, it's used in poisoned letters quite often, and obviously people aren't licking an envelope that was sent to them. $\endgroup$ Commented Dec 27, 2015 at 21:04
  • $\begingroup$ I considered answering Strychnine myself in a gel-cap to delay onset and hide the bitter taste (got busy though). IMO, this would be a better answer than ricin and has all the required characteristics in the question. The symptoms are indeed very brutal and a dead giveaway of strychnine usage. $\endgroup$ Commented Dec 30, 2015 at 2:13
  • $\begingroup$ Agreed, except I think the gel cap solution has already been rejected. $\endgroup$ Commented Dec 30, 2015 at 2:15

Low tech: amatoxin found in various poisonous fungi such as the death cap amanatia phalloides and the destroying angel amanatia virosa. It takes five hours to a day before the victim becomes ill by which time the destruction of his liver and kidneys is irreversible. An unpleasantly slow death follows. It does not taste unpleasant and kills many inexperienced and unwise foragers for edible mushrooms each year. The Roman emperor Claudius was probably assassinated this way. Beats me why anyone with enemies would ever eat mushrooms.

High tech: a Boron salt (non toxic) followed some hours later by a guided tour around a nuclear facility where the victim and his guide are exposed to a smallish neutron flux. Boron absorbs neutrons and violently fissions. I would guess that the result would be much like polonium poisoning. The guide would not be harmed.

Or polonium. Google Alexander Litvinenko for all you need to know. This is real, not fiction.

Edit I forgot maybe the nastiest of the lot. monomethyl mercury. A tiny droplet absorbed through the skin will be lethal -- after some months of suffering. (So maybe not fast enough). The assassin's biggest problem is probably avoiding poisoning himself. It soaks through much chemical protective gear as if it was not there.

Edit 2. Cholera is not generally considered a poison but an infectious illness can be administered as one. It certainly causes GI upset (!) but might not be associated with a meal if the assassin can make sure nobody else gets infected (or more evilly that a lot of innocents do get infected). Given modern medical intervention it is unlikely to be fatal but certain to incapacitate. Will also trigger a major public health emergency (which may or may not fit with your plot).

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    $\begingroup$ Aww, shoot. I was trying to find destroying angel on my lunch break for this question, then you beat me to it. $\endgroup$
    – Sidney
    Commented Dec 30, 2015 at 20:38
  • $\begingroup$ Having worked at a nuclear power plant, we used boric acid as a moderator for the fission process. I've never see it "violently fissions". See en.wikipedia.org/wiki/Control_rod and en.wikipedia.org/wiki/Neutron_moderator for more on the used of Boron in nuclear powerplants. $\endgroup$
    – thurizas
    Commented Dec 31, 2015 at 5:17
  • $\begingroup$ The nuclear reaction is that Boron-10 absorbs a neutron and fissions into Helium-4 and Lithium-7 releasing quite a few MeV of energy. I did not mean to imply any chain reaction, but anything releasing alpha radiation of that energy inside your body is really bad news. The radiation has hardly any penetrating power so outside your body this reaction is harmless. Neither fragment is radioactive. $\endgroup$
    – nigel222
    Commented Dec 31, 2015 at 12:06
  • $\begingroup$ $B^{11}$ is the most common isotope, so you'd have to do a fair amount of isotopic separation to get the desired $B^{10}$. I also assume that not just any $n$ energies would work - so this might not be practical unless the assassin knew before hand the target would go through a specific section of the nuclear reactor and set it up to supply the proper $n$ flux and energies. $\endgroup$
    – Jim2B
    Commented Jan 8, 2016 at 14:44
  • $\begingroup$ $B^{10}$ is about 20%. No need to remove the $B^{11}$, just administer five times more. Chemically boron salts have low toxicity. $\endgroup$
    – nigel222
    Commented Jan 8, 2016 at 19:05

Simple time delay

If the target takes medication, preferably hard capsules, it makes it really easy. Pick any number (or combination) of fast-acting (or slow, I suppose) poisons, fill a capsule, and place it in their medications/vitamins. Hard capsules will take a few minutes to several hours to digest, and can be made fairly precisely. Replacing the contents of capsules was used in 1982 to carry out the Chicago Tylenol murders.

Long-term ingestion

In small enough quantities, poisons are undetectable by taste or smell. Toxic metals have the ability to bioaccumulate, or build up in the body; lead and mercury are well known, but there are any number of toxic metals. Unlike some poisons, since metals are elements, they can't be destroyed, which means that they can be delivered through smoke (poisoned tobacco or candles), food, liquid, chairs, even soap - anything the victim comes in contact with. Unfortunately (for the poisoner, at least), most symptoms of metal toxicity are recognizable and often treatable before death, meaning that unless you use a really big dose, chances are, your victim is going to live to make it to the hospital. The best option would be to slowly administer small amounts over the period of a few months or weeks, waiting for you victim to begin exhibiting symptoms; early symptoms are usually ignored, but if you know what you're looking for, you can spot them easily. Once the first symptoms occur, follow up with a moderate dose. The larger dose, coupled with the built-up smaller doses, will surely kill your target.


Poisons are useful because they are cheap, easy to procure, easy to administer, and at least some of them are hard to trace. However, certain particles are deadly in doses as small as a few atoms - radioactive materials. While some radioactive materials take hours or days to kill someone, once ingested, if you really want to be sure of death, use some polonium. Polonium may be hard to come by, but it is effective. With a large enough dose, death would occur within seconds. Followed by the deaths of everyone in the house, block, and possibly city. I would suggest wrapping the dose in a lead sheath and placing that in a capsule. And hire someone else to administer it.

Death by Boom

As long as we're talking about elements, a capsule containing Caesium would be sure to make an impression. Caesium metal reacts violently with water, producing hydrogen gas, then igniting the gas in an explosion. Not only that, but a dose of 4.1 micrograms of Caesium-137 is enough to kill a dog; a dose of twice that would surely be enough to kill a human, and would be such a small dose that there is no chance it would be detected in food.

In summary

There are a lot of poisons that would fit your requirements, enough that you can choose exactly how you want your victim to die, even down to a precise time. Do you want to be sneaky or bold? Does timing matter enough to be precise to the second, the hour, or the week? Messy, or clean? Quiet, or violent? Fast death, or lingering pain? Undetectable poison, or a brash warning to others?

  • $\begingroup$ Capsules and radioactivity are out -- cesium would likely react prematurely if placed in all but the driest of foods. Heavy metals are an...interesting option, especially with the dosage schedule specified. $\endgroup$
    – Shalvenay
    Commented Dec 28, 2015 at 17:10
  • $\begingroup$ Polonium was used to assassinate Alexander Litvinenko. Google it. It fulfills most of the criteria and was almost not recognised as a murder. It is deadly if ingested but its alpha radiation cannot penetrate skin and it is no hazard to bystanders ... unless the assassin is careless and lets it leak. $\endgroup$
    – nigel222
    Commented Dec 30, 2015 at 17:54

Traditionally arsenic was used for many of the reason that you suggest, although arsenic is not a particularly fast acting poison, it has most of the other attributes you want.

Arsenic was often administered in food, seems to have little identifying taste and accumulates in the body over a period of time until the victim has ingested enough to become very ill or to die. Since the mechanism of death is interruption of the body's ATP energy cycle, death often occurs due to multiple organ failure, making it very difficult to recover from, although there are treatments that can remediate arsenic toxicity if the ingestion is discovered in time.

So don't be afraid to be a bit old fashioned.

  • $\begingroup$ Or, for a good alternative to arsenic, look up thallium. $\endgroup$
    – user11599
    Commented Dec 29, 2015 at 5:03

Rat poisons are a good start
Thallium is one, and was widely used.
Depending on dosage Thallium can be either fast or slow acting, potentially taking several weeks from the initial poisoning.
There is no known antidote once the poison has been absorbed.
Warfarin would be interesting too. Give a dose, wait 3 days, give them a bloody nose and watch them bleed to death.

Another possibility are binary weapons, where two relatively harmless agents are combined to make something deadly.
Isopropyl aminoethylmethyl phosphonite is a relatively non-toxic chemical, but when it's mixed with sulfur, it turns into highly toxic VX nerve agent.
Another example was a case of poisoned pet food where two chemicals (melamine and cyanuric acid) were put into pet food, and the resulting mixture caused a lot of pet deaths.

Some plants might be interesting.
Oleander leaves are pretty poisonous, it's pretty common, can be brewed into a tea, and the effects mimic a heart attack.

More ways to kill someone...
If you can get away from delivering the poison orally, there are other ways.
Binary poisons could be put into other things that are used together.
Makeup, hair products, shampoo and conditioner, clothing, which would be sweat activated...

Speaking of clothing, there are several poisons that can be absorbed through the skin.
Thallium, nicotine, cyanide, Dimethylmercury*, others.
Simply put some on an article of clothing, bed sheets, shoes, and some time later they die.

I also came across some interesting injested poisons.
Hemlock is pretty poisonious, but a hemlock salad is boring. Quail are immune to the poison in hemlock seeds, and love to eat them, but it makes their flesh poisonous. 6 hours after the meal the target is dead.

Rhododendrens and Azaleas are poisonous, including their nectar.
Raise some bees in hives surrounded by flowering Azaleas. Give the victim the special honey, and 6 hours later the symptoms start, followed by agony, coma, and death.

Methanol is wood alcohol which if ingested metabolizes into formaldehyde in the body. It takes 12-24 hours for symptoms to develop, by which time it's to late. Spike their whiskey and wait.

* some interesting stuff with Dimethylmercury. It's a mercury compound which is clear. It's super poisonous. It can easily go through rubber gloves. People who have smelled it said it smelled sweet before they died. It only takes 0.1 mL on the skin for a fatal dose.

  • $\begingroup$ Wafarin in small doses is a drug used to treat blood clots and in smaller doses still to prevent them. One side effect is a permanent foul taste or smell caused by the drug in the blood. So a victim might seek medical attention and survive. $\endgroup$
    – nigel222
    Commented Dec 30, 2015 at 18:33
  • $\begingroup$ It is also used as rat poison, as it keeps the blood from clotting, and allows them to bleed out. $\endgroup$
    – AndyD273
    Commented Dec 30, 2015 at 19:15
  • $\begingroup$ Binary agents are clever, but I'd be concerned that they wouldn't combine properly in someone's system before, say, being damaged by stomach acid or other biological processes. $\endgroup$
    – Wingman4l7
    Commented Jan 7, 2016 at 22:33
  • $\begingroup$ @Wingman4l7 yeah, that's a real concern. I've read about binary poisons that had fat soluble components, so you could eat one part, and then a week later have the other part, and anyone that only got a single part would be fine. Couldn't find any actual examples, and they may not exist. Another option would be non food, like the Joker in Tim Burton's Batman. First part is in the coverup, and the other in the makeup remover... Clothing maybe? Dope the t-shirt with A and the dress shirt with B, and wait for them to sweat. For that matter, put formaldehyde on their PJ's. $\endgroup$
    – AndyD273
    Commented Jan 7, 2016 at 23:23
  • $\begingroup$ The formaldehyde poisoning from clothes is a really old urban legend and there might be reasons it wouldn't work. But it's interesting. $\endgroup$
    – AndyD273
    Commented Jan 7, 2016 at 23:35

Serve some a dish with some Amanita Phalloides fungus, they are reported to taste good and don't give symptom for two or three day, and once the symptom appear, the situation is pretty bad, leading to death in a about a week


This is a somewhat alarming question due to its potential real-life applicability, but I feel reasonably comfortable recommending a poison that is rather expensive and hard to obtain, namely...


... *cough* I meant, of course

Heavy water, or $\textrm{D}_2\textrm{O}$ (a.k.a. deuterium oxide)

This exotic poison is already in our bodies, each of which contains enough naturally-occurring deuterium to make about 5-7 grams of heavy water (though most of that deuterium will actually be in the form of semiheavy water, a.k.a. $HDO$). Heavy water looks and, by some accounts, tastes just like normal water, but has sufficiently different chemical properties to normal water that when ingested in sufficient (though somewhat large) quantities, it will kill you. Specifically, experiments with animals suggest that replacing about half the water in your body with heavy water will lead to death within about a week.

So, let's tick off the criteria in the question:

Delivered by ingestion (in food or drink) -- dosing can be a single dose, or multiple doses over the span of a couple of days provided symptoms do not start until after the dosing is complete.

Check. (Well, you do have to get the victim to drink 20-25 liters of water, but I never promised you a rose garden...)

No strong off taste, odor, or color (mild tastes/odors/colors can easily be disguised/masked by putting it in an appropriate preparation though)

It tastes just like normal water -- no masking required! Check.

Delayed action (hours to a few days after dosing is complete) so that they don't associate what's happening with their last meal/drink.

Heavy water inhibits cell division, which in the short term will have no adverse effects. As I said, severe poisoning seems to set in after a few days resulting in death something on the order of one week after ingestion. Check.

No gastrointestinal symptoms once the poison starts to take effect -- again, so they don't associate what's happening with their last meal or drink.

According to Wikipedia, "The mode of death appears to be the same as that in cytotoxic poisoning (such as chemotherapy) or in acute radiation syndrome [...], and is due to deuterium's action in generally inhibiting cell division." So: Check.

Complete effect of the poison (i.e. total incapacitation) needs to be within an hour, if not within the span of minutes, after symptoms start to manifest. Needs to be incapacitating for a period of one week minimum, if not fatal.

Okay, not sure about this one. I'm rather thirsty after writing this post, I think I'll go get a drink of water...

  • $\begingroup$ I once tasted heavy water (one drop, spat and rinsed after). It tasted distinctly oily. Might have been psychological? $\endgroup$
    – nigel222
    Commented Jan 26, 2016 at 20:19
  • $\begingroup$ @nigel222 sounds cool, I'd love to try it myself sometime :-) $\endgroup$
    – user16869
    Commented Jan 26, 2016 at 20:35

Harvest your own botulinum toxin from a swelled canned good or see Uncle Fester's handbook on how to make bootleg Botox. If you mix it in the food, it would cause gastro problems but not always. It is odorless and tasteless. By the time the symptoms show up, 2-7 days, it is too late for treatment. The ER won't suspect botulism because it is just one individual. Likely misdiagnosis stroke, Eaton Lambert, Myasthenia graves, etc.

You could also dip a blade in toxin and make a very small cut on your victim.


Carbon monoxide is odorless and tasteless. Often called "The silent killer". If someone was sleeping or intoxicated they could die from breathing this without even realizing any symptoms. Depending on the concentration inhaled death can occur anywhere from 2 hours to less than three minutes. If you were to fail and the person only received acute poisoning,symptoms would include lightheadedness confusion headaches vertigo and flu like effects so suspicion would be minimal to none

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    $\begingroup$ It doesn't meet his delayed-onset requirement. $\endgroup$ Commented Dec 27, 2015 at 22:50
  • $\begingroup$ It's rather hard to deliver via ingestion, although a metal carbonyl theoretically would do the job. $\endgroup$
    – Shalvenay
    Commented Dec 28, 2015 at 5:02
  • $\begingroup$ Depending on the concentration of carbon monoxide death would occur anywhere from 2 hours to less than three minutes. Injection occurs by inhalation and being colorless odorless tasteless and initially non irritating it is difficult for people to detect. Seems to meet all his requirements unless I missing something $\endgroup$ Commented Dec 28, 2015 at 21:26
  • $\begingroup$ @PjSparkles -- wrong delivery mechanism. I suspect metal carbonyls would be a suitable vehicle for delivering it via ingestion, albeit horrifically hard to handle as they are quite volatile. $\endgroup$
    – Shalvenay
    Commented Dec 29, 2015 at 5:42
  • $\begingroup$ I wonder whether a mousse fluffed up with CO instead of air would be both tasty and deadly? $\endgroup$
    – nigel222
    Commented Dec 30, 2015 at 19:21

Another possible poison would be gamma hydroxybutyric acid or GHB it can only be detected in a blood or urine for about six hours after ingestion. GHB is sold on the black market under advertising such as "cattle Anesthetic" I believe it is considered a date rape drug or knockout preparation it causes sudden loss of consciousness with amnesia afterward. It's use is highly dangerous particularly in an overdose or in mixed intoxication

  • 2
    $\begingroup$ The question requires there to be no ill effects for at least one hour, and from what I can see about GHB, its effects are immediate and short-term, instead of lasting for one week+ (except in some cases). $\endgroup$
    – HDE 226868
    Commented Dec 28, 2015 at 22:26

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