Tetrodotoxin (TTX) is a potent neurotoxin and extremely toxic. The Material Safety Data Sheet for TTX lists the oral median lethal dose (LD50) for mice as 334 μg per kg. For comparison, the oral LD50 of potassium cyanide for mice is 8.5 mg per kg, demonstrating that even orally, TTX is more poisonous than cyanide. TTX is even more dangerous if injected; the amount needed to reach a lethal dose by injection is only 8 μg per kg in mice.


• Ingestion,

• Injection,

• Inhalation,

• Abraded skin.

Mechanism of toxicity:

• Through the blockage of fast voltage-gated sodium channels, which are required for the normal transmission of signals between the body and brain.

• As a result, TTX causes loss of sensation, and paralysis of voluntary muscles including the diaphragm and intercostal muscles, stopping breathing.

There is no cure for TTX.

I plan on using this as the biological weapon of choice by an alien species upon their invasion of Earth. Since TTX is a neurotoxin, and said aliens will have neurons, will the toxin not also affect them?


3 Answers 3


The neurotoxin might or might not affect them, we can’t tell for sure from what you have told us. However I suggest that a truly alien life form would have followed a completely different evolutionary path from the earliest origins of life. The alien’s biochemical pathways will almost certainly be completely different to ours so I doubt very much TTX would be effective against the aliens in the same way that it is to humans.

That’s not to say that it would not be toxic to them it might be to some extent, but given that this material has been selected for its ability to poison humans and human biochemistry chances are they would be much less affected.


Since TTX is a neurotoxin, and said aliens will have neurons, will the toxin not also affect them?

Why would alien biochemistry be anything even remotely like terrestrial biochemistry? Sure, they might have things which are analogous to nerves, but every other detail could (and most likely would) be totally different, in the absense of some magical panspermia precursor progenitor handwave plot.

If you're invading though, you can always just wear protective gear, right?

There is no cure for TTX.

If the aliens are advanced enough to engage in interstellar travel and invasion, I'm sure they could sort out some sort of antitoxin.

Note though that supportive care is possible for tetrodotoxin poisoning... if your breathing can be done for you, there's a good chance of you recovering after 24 hours or so. There's also some scope for treatments using monoclonal antibodies too, though quite how fast it would work I don't know... possibly not fast enough for people to keep on fighting (but really, faced with aliens capable of interstellar travel the tech-level imbalance would be such that meaningful defense is basically impossible).

Tetrodotoxin: the end of the biotic era?

If by "biotic" you meant all life on earth, then no. Animal life, maybe.

  • $\begingroup$ The 'there is no cure for TTX' was in context of human biochemistry. No antidote has been created to counter the effects of TTX on the human system. I should have specified. $\endgroup$
    – user70311
    Nov 19, 2019 at 15:46
  • $\begingroup$ I'd imagine that killing off almost all animal life would completely destroy the biosphere beyond recognition, killing almost all species of plant and fungi. Of course not all life would die, but most species of all multicellular life certainly would. $\endgroup$
    – Snowshard
    Nov 19, 2019 at 18:26

First of all, toxicity is a complex thing. It is not only LD50. TTX does no permanent damage and there is a "cure" for it: just keep lung ventilation until it is metabolized. Of cause it would not help humans during worldwide aliens invasion, but would help invaders to save each other.

More over TTX is a complex biological substance - it get destroyed by time and UV (and some natural chemicals). So all aliens would need - it just to wait certain time for TTX decomposition. TTX would left in some isolated areas for longer, but Earth in general would be habitable.


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