Sodium Azide: Cyanide’s Distant Cousin

25 Oct

Writers are constantly looking for cool poisons. I would suspect that about half the questions I receive from writers deal with poisons, usually looking for one that is cool, odd, or difficult to trace. Sodium azide is one of those.

Writers often look to the real world for story ideas. A recent case at a Harvard lab is one that might be useful. Unfortunate for those who became ill, but useful in the world of fiction. It seems that six Harvard medical researchers drank some coffee that was contaminated with sodium azide. All became ill with symptoms that range from dizziness to loss of consciousness. Fortunately none of them died. The question that always arises in such workplace exposures is whether this was accidental or intentional. Apparently an investigation is ongoing.

In the fictional world, my friend Kathleen Antrim used sodium azide in a clever way to off a US senator in her excellent book Capital Offense.

Sodium azide is an odorless white solid that easily dissolves in water or other liquids. When dissolved, it releases a pungent-odored toxic gas and inhalation of this gas can lead to poisoning. It can also be ingested and has the unusual property of rapidly absorbing across the skin. Simply touching the compound or having the liquid it is dissolved in splashed on you could lead to poisoning. This means lab workers who use this compound must be very careful but for fiction writers it offers a world of potential plot events.

Sodium Azide is often discussed in the same sentence with cyanide. Even though they are distinctly separate chemicals, they have many properties in common. They can enter the body by ingestion, inhalation, or through the skin. Both interfere with the ability of the cells within the body to use oxygen and it is this interruption that leads to rapid death. The symptoms of exposure to either of these compounds are similar and might include: chest pain, shortness of breath, dizziness, headache, rapid heartbeat, nausea and vomiting, a low blood pressure with shock, loss of consciousness, sometimes seizures, and death.

Writers are often looking for toxins that mimic a heart attack and, like cyanide, sodium azide fits the bill. The victim would develop chest pain, shortness of breath, become weak and dizzy, collapse, and die. Exactly as would happen in a major heart attack that resulted in sudden death. Since neither cyanide nor sodium azide show up on a routine drug screen, the medical examiner must have a suspicion that such a chemical was involved before he would go to the time and expense of testing for it. With cyanide the medical examiner might notice the bright red color of the blood, the skin, and the internal organs of the victim, a coloration that is due to a chemical reaction between the cyanide and the hemoglobin found within the red blood cells. Sodium azide has no such reaction and so the bright red color is not present. Your sleuth will need some other reason to persuade the ME to do the testing, but that’s what storytelling is all about.

CDC Article

Northeastern University Article


13 responses to “Sodium Azide: Cyanide’s Distant Cousin

  1. Rose

    October 25, 2009 at 4:17 pm

    Sodium azide is an explosive used in airbags. J.A. Jance used this as a potential threat in her Joanne Brady series.


  2. Susanne Saville

    October 26, 2009 at 10:31 am

    Poisoned coffee…wow…you’d certainly be looking askance at your co-workers after that.


    • D.P. Lyle, MD

      October 26, 2009 at 10:59 am

      And I just heard on the news that they are now treating this as a criminal case. Not sure what evidence they have but it looks like someone might have had a grudge of some kind. That’s a common motive when someone tries a mass poisoning.


  3. Catherine

    October 27, 2009 at 12:12 pm

    This is my 1st visit to this site -please be kind if I’m a bit “out there”, but then, you’re writers & so may understand. Whether it’s just a raging case of woman’s intuition or writers rampaging imagination, I’ve been intrigued by the case of the woman who drove the wrong direction down the freeway, crashed & burned, killing her nieces & others in another car this past July. The supposition is she was dead drunk, but no one seems ever to have seen her dead drunk or to have come forward saying she bought a lot of liquor or hung out in bars or whatever, which seems a bit odd. In the meantime, she’s been demonized by all the shrieking heads on the talk shows. It’s been reported she stopped at a fast food restaurant & appeared sober & lucid. This thing at Harvard with the sodium azide set off my imaginative juices again; I recall a friend who worked in the deli at a market in high school who told of spiking the chocolate pudding with Ex-Lax -if someone threw something into coffee or whatever & people died, they might not be in a big rush to come forward. Does anyone think it’s remotely possible you could have this result with sodium azide? The other memory that got prodded by this idea is the late Henri Paul in the Princess Diana case….as I said, please be kind, I’m new here, but I’m counting on writers being more open to possibilities than the average scientist.


    • D.P. Lyle, MD

      October 27, 2009 at 2:01 pm

      I’m glad my blog makes you think and consider. That’s its purpose. But I’m not sure what point you’re making that required you to apologize for it ahead of time. If your point is that we scientist are closed minded, that is simply not true. We ask questions all the time. That’s what science and research is all about. If your point is that the media blows everything out of proportion, then you are correct. If your point is that just because a witness or two say that a possible intoxicated driver APPEARED normal and if so no investigation should follow, then I must disagree. In the Harvard case, if someone did put the azide in the coffee they wouldn’t come forward. Criminals usually don’t. They would rather do everything they could to cover their crime. But not to investigate, if the police believe that it is POSSIBLE some criminal activity was involved, would be a breach of the public trust. The question is not whether they were exposed–the scientists proved that they were–but why and how and was someone responsible in a criminal way. That’s why the Boston police are investigating. Unfortunately things like this aren’t rare. In 2003, church members at a Maine church were poisoned by Arsenic that I think was secreted in coffee. In 1984, the Rajneeshes in The Dalles, OR sprayed produce in local grocery stores with a potentially deadly bacterium known as Salmonella in what might have been the first bioterrorism attack in the US. And Stella Nickell put cyanide into Excedrin, placed it on store shelves, and killed an innocent person is an attempt to cover the murder of her husband by her hand yet make herself eligible for extra insurance benefits if his death was deemed accidental and not natural from his severe emphysema. Each of these cases was solved because the police asked questions and investigated the deaths. And Henri Paul? The scientist determined that his blood alcohol level approached 1.8, which is 2.5 times the legal limit. That likely contributed to the accident. Of course had the accident happened in a major US city Princess Di might very well have survived. The French system of treating in the field rather than running to the nearest trauma center doomed her from jump street. Took over 90 minutes to get her to real help. Please visit often and offer comments anytime. You thoughts and opinions are welcome.


      • Catherine

        October 27, 2009 at 7:25 pm

        Dr. Lyle, thanks so much for your reply -I didn’t mean to say closed minded, but sometimes I wonder if too many scientists tend to put restraints on their imagination when they might find the right avenue for research more quickly if they allowed their ideas to be a bit more adventurous earlier on in the process -obvious why I did not aspire to a career in any scientific field I’m sure.

        We agree completely on the media and proportion, I felt rather that perhaps the investigation might not be thorough enough -that it might be quite normal and understandable to conclude the answer is the most common one. As far as anything a person might have consumed, I would think it might have been contaminated by accident ( i.e. pesticide, which bars & restaurants do use), or as an ignorant prank, not through a deliberate attempt to kill. What intrigued me about the sodium azide is that it works so quickly even in a small dose and is something out of the mainstream and not normally looked for. Is it possible that its effects could mimic intoxication or produce a high stomach or blood alcohol content at some point -perhaps even in concert with another substance? And what might the effect be if alcohol was ingested close to the time the person was exposed to the sodium azide?


      • D.P. Lyle, MD

        October 28, 2009 at 9:04 am

        The symptoms would then be a combination of those from the azide and the alcohol. If the blood alcohol level were very high–say over .30 or so—the ME might think death was from that and never check for sodium azide—which no one would ever think of except in a lab situation where this chemical was used as was the case at Harvard.


  4. wolfemann

    October 29, 2009 at 11:40 am

    Hmm… about when was Sodium Azide developed? Could be a handy tool for some of my projects.


    • D.P. Lyle, MD

      October 29, 2009 at 11:53 am

      I couldn’t locate any info on when sodium azide was discovered/created but it has been around for a long time.


  5. iriserlings

    January 21, 2013 at 8:52 pm

    How interesting… 1. Where could the average Jane get a hold of sodium azide? 2. Would it work if one mixed it with a body cream/lotion and if so, how much of it would it take to do the deed? Would a blob from the victim´s handlotion bottle suffice? Or is a full-body post shower skin treatment needed?
    Btw. I seem to recall reading that a tox screen from the woman driver revealed marijuana and alcohol.


    • D.P. Lyle, MD

      January 22, 2013 at 5:58 am

      Very difficult to come by but it would easily work in any topically applied substance if the dose were large enough–and it only takes a small amount.


  6. Lisa Binion

    October 10, 2013 at 5:16 pm

    How could one realistically have a character obtain sodium azide? I want what I write to be somewhat believable.


    • D.P. Lyle, MD

      October 10, 2013 at 5:25 pm

      Very difficult but it is used in air bags and other manufactured products so your character could have an in there or maybe at a pharmaceutical supply house—something like that.



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