How does one define “deadly”? In snake terms, of course. Would it be the potency of the venom? As in, Snake A can kill 50 people with one bite and Snake B can kill 1000, therefore snake B is the more deadly. Does it really matter whether you’re 50 or 1000 times deadder? Perhaps it’s more important how quickly the venom kills you, or in how many ways the venom can kill you (suffocation and bleeding out at the same time? Awesome!). Maybe it’s more relevant how likely you are to actually encounter and get bitten by the snake in question (if it can kill 1000 people in 0.5 seconds with a single bite, but only lives on the top of Mount Everest, is usually unconscious and always exceptionally friendly, how much of a threat is it?). With these points in mind, here are some snakes that can definitely be considered deadly.

Black Mamba, Sub-Saharan Africa
Africa’s longest venomous snake at up to 4.2m (14ft) long, and second only to the king cobra worldwide, the black mamba is an impressive creature. Named for its pitch black mouth, this snake is not only large, but extremely fast, with a striking speed of up to 5.4 metres pers second (17.7ft). A single bite can kill anywhere from 10 to 40 people, and when a black mamba decides to go for you, it really means business. These snakes deliver repeated, lighting-fast bites, all of which envenomate (no dry bites here). Their neurotoxic venom is also highly potent and the most rapid acting of any known snake species, with symptoms showing within 10 minutes. Untreated, bites have a 100% mortality rate. Black mambas have a reputation for being extremely aggressive, but this isn’t entirely fair. They are, in fact, very shy and highly defensive. However, considering the result of getting too close to one is certain death (without antivenom) and the black mamba’s idea of “too close” is around 40m (130ft) away, you might not notice the difference.

Boomslang, Sub-Saharan Africa
Of all the snakes in Africa, the boomslang has the most potent venom. Indeed, the amount needed to kill a human is so tiny, it would barely be visible to the naked eye. Unlike most venomous snakes, the boomslang’s fangs are situated in the back of the mouth, meaning it has to essentially “chew” its venom into its prey. This has lead to the common misconception that the relatively small-mouthed boomslang is incapable of envenomating a human, but oh no! They are more than able, as their mouths open a whopping 170˚. Following a bite, the haemotoxic venom affects the blood’s ability to clot, so victims die slowly from uncontrollable bleeding from each and every orifice and mucus membrane (delightful!). Fortunately, however, boomslangs are remarkably shy and docile snakes, and bites are very rare, almost exclusively happening to snake handlers. As its name suggests, the boomslang (“boom” being Afrikaans for tree, “slang”, snake) is highly arboreal, living and hunting mostly in trees. As such, your chances of provoking an attack from a wild boomslang are very small (unless you climb a lot of trees in sub-saharan Africa, for some reason), and as this author can personally testify, having met a few (not smugly at all), if you leave them alone, they’ll do the same.

Coastal Taipan, Australia, Polynesia
Growing up to 3m (9.8in) in length, Australia’s largest and third-most venomous snake is not to be trifled with. Though they generally avoid interacting with humans, coastal taipans are highly defensive and nervous creatures, and can be triggered by even the slightest disturbances (like most of Gen Z). They don’t just strike once, either. Triggered coastal taipans are known to deliver a series of rapid-fire bites, often before the offender is even aware of their presence. Though their venom is not as potent as their inland cousins’, a single bite is still enough to kill up to around 59 people. Depending on the amount of venom injected, victims can die as soon as 30mins after the bite, though more often they last 3-6 hours. Not all bites envenomate (around 80%), but when you’re being bitten repeatedly with the rapidity of machine gun fire, this is not a very comforting statistic.

Inland Taipan, Australia
In terms of potency, the inland taipan may very well hold the title of “world’s deadliest snake”. A single bite from an inland taipan contains a cocktail of toxins capable of killing some 100 adult humans. Yet remarkably, the grand total of people known to have fallen victim to this snake is zero. That’s right: not one human has ever been killed by an inland taipan (that we know of). Why? Because unlike its decidedly neurotic coastal cousin, the inland taipan is seriously non-confrontational. Snake handlers have even described them as “puppy-like” (not sure what kind of puppies they’ve met, but I’ll take their word for it). Their general shyness, coupled with the fact that they live in remote, largely unoccupied regions of the Australian Outback, means that humans have little to fear from these toxic powerhouses.

Eastern Brown, Australia, New Guinea
In terms of numbers of victims, the eastern brown snake is far more dangerous to humans than either of the taipans. These snakes are responsible for more human deaths than any other snake in Australia. This is largely because brown snakes tend to occupy the same areas as humans, so encounters are not infrequent. They have a reputation for being fairly jumpy and nervous, leading to the misconception that they are aggressive. Interestingly, their fangs are very short, at under 4mm (0.1in), and they do not inject much venom when they bite, but their venom is so toxic that even an apparently minor bite can kill in under an hour, if left untreated. However, the majority of bites from brown snakes happen when people are trying to kill them (fair response, really), and so would be entirely avoidable if people weren’t such bastards. Despite brown snakes’ potential lethality and the human propensity to fuck-around-and-find-out, only one or two people die from brown snake bites per year.

Russell’s Viper, South Asia
In terms of victim numbers, Asian snakes put both their African and Australian counterparts to shame. The Russell’s viper alone is responsible for over 25,000 human deaths annually, more than all venomous snakes in sub-Saharan Africa combined. This is, at least in part, due to the fact that Russell’s vipers often live in highly populated areas, as they eat the rats and mice these areas attract (if you’re thinking “great for pest control”, you’re right, but maybe just get a cat). The venom of the Russell’s viper is interesting (horrible, but interesting). The bite itself is extremely painful, and causes blistering, swelling, tissue death and bleeding from the gums within minutes. The venom has a rather horrible effect on the kidneys, and even with treatment, victims may experience long term renal issues or even failure. And if the kidney failure and general damage to vital organs don’t get you, you might well succumb to septicemia from massive tissue damage, so there’s always that to look forward to. Recent studies have also shown that rising temperatures due to climate change make the venom even more deadly (thanks, politicians!). On the plus side, Russell’s vipers do at least give good warning. When threatened, they puff themselves up and hiss like an enraged pressure cooker (another very scary thing) and only bite if you ignore the warning.

Common Krait, South Asia
Like the Russel’s viper, the common krait is a member of Asia’s “Big Four”, the snakes responsible for the highest number of human deaths on that continent. The venom of the common krait is neurotoxic, causes paralysis and death in as little as 4-8 hours. The tricky thing about common krait bites is that people often don’t notice they’ve actually been bitten until it’s too late. How does being bitten by one of the most dangerous animals on the planet simply escape one’s attention? Well, for one thing, the fangs of the common krait are tiny: only about the diameter of a children’s vaccination needle and less than 3mm (0.1in) long. Secondly, the venom doesn’t usually cause any immediate symptoms. Thirdly, common kraits are nocturnal, so bites often occur when people move in their sleep and startle the snakes. Unfortunately, even treatment with antivenom may not be enough to save victims. While the antivenom can be effective at neutralising the venom (though isn’t always), once paralysis sets in, it is irreversible.

King Cobra, Asia
The aptly-named king cobra is the largest venomous snake in the world, measuring up to 5.8m (19.2ft) long, with an average length of 4m (13ft). The aptly-named “king of snakes” does what many monarchs throughout history have done and lives off its subordinates, i.e. it eats other snakes, including highly venomous Indian cobras, kraits and essentially anything it can fit in its mouth. Unsurprisingly, the king cobra bite packs a powerful punch. Not only is the venom highly toxic, but the sheer volume these massive snakes deliver is enough to kill an adult elephant in 3 hours. In humans, death can occur in as little as 30 minutes. Oh yeah, and they growl. They don’t hiss, they growl. Yet as terrifying as they may seems, king cobras are actually very shy and avoid human contact. They only bite if they are cornered and their warning signs are ignored (how anyone could ignore a snake the length of a car which growls like a dog is a mystery, but is has happened). They also make very caring mothers, with females building and protecting their nests during incubation, then politely leaving shortly before hatching to avoid uncontrollably eating their babies.

Saw scaled viper, North Africa, Asia
Topping the list for single-handedly killing more humans than any other venomous snake is the saw-scaled viper. This tiny, adorable-looking snake causes tens of thousands of human deaths annually, from equatorial Africa, all the way through the Middle East to India. Measuring as little as 30cm (12in) long, they are an unlikely candidate for the “world’s deadliest snake”. Their “success” in achieving this is partly because they are so widely distributed, mainly because the term “saw scaled viper” actually refers to 12 separate species. These snakes get their name from the shape of their scales (obviously), which they rub together when threatened, producing a very-scary-and-not-at-all-cute rasping sound. Saw-scaled vipers, like many snakes, are misrepresented as “aggressive”, when in fact they are simply defensive. They can be a little overzealous in their defense, however, and have been known to overbalance in their threat displays, accidentally launching themselves towards the threat, leading to the commonly held belief that they chase people.

Regardless of how you classify “deadly”, all of these snakes have a place on the list of “things you don’t want to get bitten by”. However, in the vast majority of cases, snakes don’t want to hurt you. They don’t actually want anything to do with you. Venomous snakes do not (and physically cannot) consume humans, so have no motivation to attack. Like any creature confronted with something much larger than itself, snakes view humans as threats to their safety (as we very often are). As such, snakes would much rather avoid us than attack us, if they can. So, how do you avoid being bitten? Leave them alone. And if you and a snake find yourselves in the unfortunate position of bumping into each other accidentally, as one might with an unpleasant colleague or regrettable one-night-stand (or both, if you make really bad life choices), do what you would normally do: stare at each other blankly for a moment, then back away slowly and quietly.

References:

“Immediate First Aid for bites by Black Mamba (Dendroaspis polylepis polylepis)”. University of California at San Diego.

Spawls S, Branch B. (1995). The Dangerous Snakes of Africa. Ralph Curtis Books. Dubai: Oriental Press.

“Coastal Taipan”. Australian Museum.

Sutherland, Struan K.; Sutherland, John (2006). Venomous Creatures of Australia: A Field Guide with Notes on First Aid (5th ed.). South Melbourne, Victoria: Oxford University Press. pp. 22–23. ISBN 978-0-19-555330-7.

Mercurio (2016-08-30). Understanding Toxicology. Jones & Bartlett Publishers. ISBN 978-0-7637-7116-4

Marais, Johan (2004). A complete guide to the snakes of southern Africa (New ed.). ISBN 978-1-86872-932-6

Daniel, J.C. (2002). “Russell’s viper”. The Book of Indian Reptiles and Amphibians. Oxford, USA: Oxford University Press. ISBN 0-19-566099-4

https://www.gavi.org/vaccineswork/surprise-factor-makes-indias-deadliest-snake-even-more-toxic

Blessmann, Joerg; Kreuels, Benno (April 2024). “Urgent administration of antivenom following proven krait bites in Southeast Asia irrespective of neurotoxic symptoms”. PLOS Neglected Tropical Diseases. 18 (4) e0012079

“Saw-scaled viper”. Encyclopædia Britannica.

Chanhome, L.; Cox, M. J.; Vasaruchapong, T.; Chaiyabutr, N.; Sitprija, V. (2011). “Characterization of venomous snakes of Thailand”. Asian Biomedicine. 5 (3): 311–328.

Tweedie, M. W. F. (1983). The Snakes of Malaya. Singapore National Printers.