What happens when snakes strike

From the serpent’s seduction of Eve to the 2006 action thriller ‘Snakes on a Plane’, snakes haveB fascinated and terrified cultures for millennia. 

Their mystique rests largely on their weapon of choice: venom - a complex mixture of toxins evolved to subdue prey and deter threats. 

However, our team at the Section for Biologics Engineering (SBE) at the Technical University of Denmark has just taken a big step toward changing that. 

We have developed a new kind of antivenom that protected mice from the deadly effects of 17 different venoms from snake species across sub-Saharan Africa, including cobras, mambas, and the rinkhals. 

You can read more about our study and the new antivenom in this Videnskab.dk article. 

Below, we take a closer look at the three most important types of toxins that the new antidote protects against.

Different toxins cause different damage

Snakes don’t usually have humans on the menu, but their venom doesn’t exactly discriminate. Our biology is similar enough to their natural prey that when we’re bitten, the results can be devastating.

The first step toward an antivenom that hopefully can protect people against many different snakebites is figuring out which toxins do the most damage, and how.

Snakebites tend to harm people in three main ways, each linked to a specific group of toxins. These are also the major targets of our antivenom research, both in our recent publication in Nature and in our ongoing work.

To show just how diverse these effects can be, here are three real stories of snakebites and the

very different ways venom can harm the human body.

Case 1: A silent cry – neurotoxin

In a quiet Thai village, a young boy ran to his grandmother, crying, “An animal bit me!” Moments later, he collapsed. By the time he reached the hospital, he had stopped breathing and fallen into a coma.

For two days, doctors were baffled until a nurse spotted two small puncture wounds on his ankle. Without delay, the doctor administered cobra antivenom. The result was almost miraculous: the boy opened his eyes and took his first breath in days.

This isn’t a story of jungle horror. It’s a real-life example of how neurotoxic snake venom works.

Cobras, like other elapids, inject potent toxins that paralyze the nervous system. Most of these toxins, known as neurotoxins, belong to a group called 3-finger toxin family, named after their shape.

They block nicotinic acetylcholine receptors at neuromuscular junctions, the critical sites where nerves signal muscles to move.

Symptoms usually begin in small muscles that control eyelids, speech, and swallowing. Watch for those first. But before limbs go limp, the most dangerous effect comes when the diaphragm is paralyzed and breathing stops.

Quick administration of antivenom can reverse the symptoms, but recovery depends on the venom’s composition and how quickly treatment begins.

Case 2: A painful pump - tissue damage

Half a world away in North America, a man picked up a rattlesnake (just for fun and it looked cool). Within seconds, it bit him. 

Pain spread through his arm like wildfire. Swelling followed fast, making his limb feel as though it were being pumped with air. Unlike the boy from Thailand, he remained conscious, but the venom was destroying tissue from within. 

The swelling and pain weren’t random. It was venom chemistry at work. One toxin, snake-venom metalloprotease, speeds venom spread by breaking down the scaffolding that holds cells together. 

Another group, phospholipase A₂ enzymes, damages the fatty layers of cell membranes. Together, these toxins mount an aggressive, almost unstoppable attack on tissue.

Antivenom helped, but slowly. Without timely treatment, his arm could have turned black or even required amputation. What started as curiosity ended with two weeks in the hospital and a painful reminder to respect venomous wildlife.

Case 3: A bloody day - haemotoxicity

In South Asia, a farmer working in a rice field was bitten by Russell’s viper. Four hours later, he was bleeding from his gums, his wound, and even in his urine. 

Blood tests showed severe anemia, his red blood cells were being destroyed faster than his body could make them. 

The venom clearly disrupts the body’s system for keeping clotting and bleeding in balance. Normally, a coagulation cascade forms fibrin, which helps blood clot. 

But toxins such as snake venom serine proteases interrupt this process, either by weakening fibrin or preventing its formation altogether. 

The result is uncontrolled bleeding, as in this case. Paradoxically, some other toxins do the opposite. They trigger excessive clotting, especially in small blood vessels, cutting off blood flow to vital organs, such as the kidneys. 

Both can happen at once, depending on which toxins dominate in the venom. When clotting toxins dominate, they can use up the body’s clotting factors, leaving none to stop bleeding elsewhere.

Although antivenom controlled the bleeding, the damage was already done. His kidneys were failing, and he spent the next week on dialysis before stabilizing.

This is not all...

Beyond nerves, skin, and blood, venom can damage almost any organ it reaches: the heart, brain, muscles, and more. Thankfully, antivenoms do more than save lives. They can prevent long-term damage, preserving quality of life after a bite.

But venom isn’t the only threat. Snakes often carry harmful bacteria in their mouths, especially from prey. Those bacteria can enter the wound and cause infections, leading to swelling, tissue death, and even death if left untreated.

Some venom proteins can also trigger strong allergic reactions. In rare cases, this causes anaphylaxis, a life-threatening allergy. While antivenom can’t stop allergic reactions, quick medical care with the right medication can.

You might wonder: Why not just eliminate the snakes? Well, snakes aren’t aggressive by nature. They bite when they feel threatened. And while new antivenoms are making treatment better, the best defense remains the same: avoid and respect snakes in the wild.