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How poisonous is a viper snake?

How poisonous is a viper snake?

Viper snakes are a type of venomous snake that can be found on every continent except Antarctica and Australia. There are around 300 different species of vipers worldwide, including rattlesnakes, copperheads, and puff adders. Vipers produce a venom that is highly toxic and used to immobilize and digest prey. The potency of viper venom varies between species, with some being much more poisonous and deadly to humans than others.

Venom Potency

The toxicity of a viper’s venom is measured by its LD50 value. This refers to the dose that is lethal to 50% of tested animals, usually mice. The lower the LD50 value, the more potent and poisonous the venom. Here are the LD50 values for some common viper species:

Viper Species Venom LD50
Eastern diamondback rattlesnake 0.4 mg/kg
Western diamondback rattlesnake 2.3 mg/kg
Black mamba 0.32 mg/kg
Gaboon viper 0.55 mg/kg
Puff adder 0.4 mg/kg
Russell’s viper 0.111 mg/kg

As you can see, there is considerable variation in venom toxicity between different viper species. The eastern diamondback rattlesnake, black mamba, and puff adder are among the most lethal, while the western diamondback rattlesnake has venom around 5-6 times less toxic. However, even vipers with less potent venom can still inflict very serious bites.

Venom Composition

What makes viper venom so poisonous? These snakes have a venomous cocktail containing many different toxins and enzymes, each with their own distinct effects:

  • Hemotoxins – Disrupt blood coagulation and destroy blood vessels and tissues.
  • Myotoxins – Break down muscle fibers and cause muscle paralysis.
  • Neurotoxins – Interfere with nervous system signaling and cause paralysis.
  • Necrotoxins – Cause cell and tissue death at the bite site.
  • Hyaluronidases – Help spread the venom through tissues.

Different vipers have varying proportions of these toxins in their venom, contributing to differences in effects. For example, rattlesnakes tend to have more hemotoxins while cobras have large amounts of neurotoxins.

Clinical Effects of Viper Bites

When someone is bitten by a viper, the clinical effects depend on the snake species and amount of venom injected. However, common symptoms and signs include:

  • Immediate, severe burning pain at the bite site.
  • Swelling, bruising and tissue damage around the bite.
  • Bleeding from the fang marks and wounds.
  • Nausea, vomiting and profuse sweating.
  • Rapid heart rate and low blood pressure.
  • Bruising, abnormal bleeding and clotting problems.
  • Kidney damage and dark brown urine.
  • Muscle weakness progressing to paralysis.
  • Impaired vision and difficulty speaking and swallowing.
  • Seizures, coma and respiratory failure in severe cases.

Without antivenom treatment, viper bites can quickly become fatal depending on the amount of venom injected. Even with treatment, up to 20% of viper bites can still result in death. However, the vast majority of bites are from smaller snakes or are “dry” bites without venom, resulting in less severe symptoms manageable with supportive medical care.

Factors Affecting Bite Severity

Several factors influence how poisonous a particular viper bite ends up being:

  • Snake species and size – More toxic vipers and larger snakes inject more venom.
  • Amount of venom injected – “Dry” bites have none while others have large doses.
  • Location of the bite – Bites to the head, neck and trunk are most dangerous.
  • Time elapsed before treatment – The longer the delay, the more venom is absorbed.
  • Victim health and age – Children, elderly and sick patients fare worse.

For example, a bite from a small rattlesnake that injects little venom into the leg of a healthy adult may cause moderate symptoms. But a big eastern diamondback delivering lots of venom deep into the torso of a child has much higher risks of being lethal.

Snake Identification

When someone suffers a suspected viper bite, identifying the snake species involved can help assess potential severity and guide treatment. Some distinctive features of vipers include:

  • Thick, triangular heads.
  • Vertical slit-like pupils.
  • Paired fangs that fold back when mouth closed.
  • Keeled scales giving a rough texture.
  • Stocky, short bodies.
  • Distinctive patterns like diamonds, zigzags or chevrons.
  • Rattles on tails of rattlesnakes.

Photos, descriptions of snake markings/colors and details on where the bite occurred can help experts determine the species. Antivenom designed to target specific venom toxins works best, so identification is useful for optimizing treatment.

First Aid for Viper Bites

If bitten by a viper, quick first aid can buy time until medical treatment:

  • Remain calm and still to avoid increasing venom circulation.
  • Remove any constrictive clothing/jewelry near the bite.
  • Wash the bite with soap and water if possible.
  • Immobilize the bitten limb and keep it lower than the heart.
  • Apply a wrapped cold pack to help slow venom spread.
  • Monitor vital signs and note any symptoms for doctors.
  • Seek emergency medical help immediately.

Do NOT do things like cut/suck the bite, apply a tourniquet or ice directly. Leave snake removal to professionals when possible. Staying relaxed and getting rapidly to a hospital are the priorities.

Medical Treatment

With prompt and proper medical care, the danger of viper bites can be substantially reduced. Treatment guidelines include:

  • Measuring and monitoring blood coagulation function.
  • IV fluids and medications to maintain blood pressure.
  • Tetanus and antibiotic prophylaxis.
  • Pain control medications.
  • Antivenom injection to neutralize venom – multiple vials are often needed.
  • Respiratory support if needed.
  • Surgical debridement and drainage of severely damaged tissue.
  • Dialysis for kidney failure.

Rapid administration of the right antivenom can dramatically improve outcomes after viper bites. However, antivenoms carry risks of allergic reaction and serum sickness, so must be dosed properly under medical supervision.

Prevention of Viper Bites

The best way to avoid harm from viper snakes is to steer clear of them when possible. Prevention tips include:

  • Learn how to identify local venomous snakes.
  • Avoid reaching blindly into crevices and underbrush.
  • Wear protective boots and gaiters in snake country.
  • Keep hands and feet out of tall grass and leaf litter.
  • Don’t try to handle or kill venomous snakes.
  • Be very careful when stepping over logs or rocks.
  • Use care and carry a flashlight when hiking at night.
  • Keep homes and yards free of brush piles and debris that attract snakes.

Staying alert and giving snakes space is key. Also, keeping mobile phones within reach to call for help can aid rapid treatment.


In summary, viper snakes have highly poisonous venom that can cause severe tissue damage, bleeding and paralysis when injected in bites. However, the level of potency varies greatly between species, with some being far more dangerous than others when significant amounts of venom are delivered. Prompt first aid and emergency antivenom treatment are crucial for surviving severe viper bites. But with proper precautions, most potentially dangerous encounters with these snakes can be avoided.