Russian opponent Alexeï Navalny was killed by a very exotic poison according to the United Kingdom, Sweden, France, Germany and the Netherlands: epibatidine, a toxin from Latin American dart frogs. “Unfounded” accusations according to Russia, suspected on several occasions of having used particularly virulent poisons.

Published on: 02/16/2026 - 5:41 p.m.

It is a rare poison coming from a frog that only lives in a few Latin American countries, such as Peru. The very toxic epibatidine was allegedly used to poison Alexeï Navalny, the famous Russian opponent of Vladimir Putin, who died in prison on February 16, 2024, two years ago to the day.

In any case, this is what five European countries say following a joint investigation: “The United Kingdom, Sweden, France, Germany and the Netherlands are convinced that Alexeï Navalny was poisoned with a lethal toxin,” declared their representatives on the sidelines of the Munich Conference on International Security, Saturday February 14.

From polonium to epibatidine

Laboratory analyzes on a European scale made it possible to isolate in samples of Alexeï Navalny's skin traces of "a deadly toxin present in the skin of Ecuadorian dart frogs, [epibatidine]", affirmed the five States.

“We firmly reject these accusations, which are biased and not based on anything concrete,” responded Dmitry Peskov, the Russian president’s spokesperson.

But these findings and the announcement made at the largest international security conference allowed the dart frog and its epibatidine to attract global attention.

Also read: Novichok, a Cold War poison even more deadly than sarin

This exotic poison is added to polonium, the radioactive substance used to poison Alexander Litvinenko in 2006, and to Novichok, the nerve agent which was used in the attempted assassination of former double agent Sergei Skripal in 2018. Each time, Moscow is accused of being at the origin of these poisonings.

In the case of Alexeï Navalny, “the symptoms [before his death] correspond to what is known about the effects of epibatidine”, underlines the independent Russian media Meduza. Exposure to this poison causes muscle contractions, paralysis, convulsions, slowing of the heart rate, respiratory failure, Jill Johnson, a British toxicologist, detailed to the BBC.

Almost everything has been said in the media – including France 24 – over the last two days about the dangerousness of this toxin “200 times more powerful than morphine”.

Discreet and deadly

But “why would Russia, which already detained Alexeï Navalny, need to use such an exotic toxin to eliminate this opponent?” asks Kevin Riehle, specialist in intelligence services at Brunel University in London.

The Russian security services "could have used any other poison on Alexeï Navalny, or simply let him die in prison", adds Luca Trenta, researcher in international relations at the University of Swansea (Wales) and specialist in assassination operations by the secret services.

From a toxicological point of view, the use of epibatidine can be justified by its effectiveness. “For other more well-known nerve agents, such as sarin or Novichok, it is possible to counter the effects with very good medical care applied very early. But I have no idea how epibatidine poisonings are treated, and I have not seen anything conclusive on this,” says Alastair Hay, toxicologist at the University of Leeds.

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There is only one documented case of an individual exposed to this poison and who survived: a laboratory worker in the United States in 2010. But the story of his rescue, with the help of antihistamines, "raises a lot of questions", Alastair Hay wishes to qualify.

A substance that is difficult to counter… and detect. “It only takes a relatively small dose to be fatal, which means that traces in the body are difficult to find during analyses,” explains the British toxicologist.

It’s even less obvious if you don’t know what to look for. And since epibatidine appears never to have been used before in cases of poisoning, it is not the first toxin that analysts will try to identify in the body.

This poison is also quite simple to administer: “We know that we can be poisoned by ingesting it, by being exposed to it through the skin and, although it is less documented, it is probably a poison that can act by being inhaled,” explains Alastair Hay.

Navalny, a guinea pig?

All these aspects are not enough to justify the use of epibatidine against an opponent already in poor health and behind bars in Russia, believes Kevin Riehle. “The only reason that comes to mind, and which is quite monstrous, would be that Alexei Navalny served as a guinea pig for this poison,” he says.

Indeed, this toxin "has been known for decades by scientists who have sought to use it as an analgesic. The substance can today be reproduced in the laboratory", confirms Alastair Hay. “Developing this weapon is not difficult,” but it is still necessary to ensure its effectiveness, recognizes Luca Trenta.

For Moscow, it can also be a way of reminding us that "their laboratories, which have been working for decades on the development of poisons, are still capable of developing new complex and effective toxins", underlines Mark Galeotti, specialist in security issues in Russia and director of the Mayak Intelligence consulting firm.

The use of epibatidine serves, according to this expert, to create “constructive ambiguity”. “On the one hand, the Russian authorities could hope that the poisoning would go unnoticed; but on the other, if it was discovered, they might as well use a rare and exotic poison,” notes Mark Galeotti. This way of striking people's minds with images of deadly frogs and venom from very far away "makes it possible to create a story which demonstrates how far the Kremlin is prepared to go to silence its critics", specifies this specialist.

Finally, “the use of poison is also a question of revenge against opponents of Russian power,” assures Luca Trenta. And to make the death of a troublemaker of the caliber of Alexeï Navalny a resounding example, what better way than with an exotic, unique and particularly virulent poison?

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