Snakebite Envenoming: Fast facts

  • Snakebite envenoming is the disease that result when a snake injects poisonous venom, in sufficient amounts, following a bite.
  • The snake bite prevalence in poor countries is dire relative to wealthy ones because of below par preventative measures and poor access to care. The treatments are expensive, the people who need them often can’t afford them, and in some cases people can’t make it to the hospital in time to save lives and limbs. And even when people do reach hospital, sometimes the clinicians are not trained adequately, and often treatments are not available.
  • Another major challenge is that many of the anti-venoms available are not actually effective. Different types of snakebites need different types of anti-venom. In Africa, for example, up to 90% of available anti-venom is thought to be ineffective. 
  • A snake bite, however, does not necessarily translate to envenomation. In many instances venomous snakes will bite in self-defense and inject no venom at all–such bites are referred to as dry bites. A potentially deadly snake may also inject just a small amount of venom – far too little to do serious damage. Observation in the emergency department for 8-10 hours may be needed for dry bites to ensure lack of progression of symptoms.
  • Venomous snakes have two fangs that deliver venom when they bite. A venomous snake bite will usually leave two clear puncture marks. In contrast, a nonvenomous bite tends to leave two rows of teeth marks.It is, however, difficult to tell the difference between puncture wounds from venomous and nonvenomous snakes. People should, therefore, treat all snake bites as though the snake were venomous and seek immediate medical attention. 
  • Puff Adder venom is potently cytotoxic, causing severe pain, swelling, blistering and in many cases severe tissue damage. Polyvalent antivenom is effective and should be administered sooner rather than later.
  • The venom of Black and green mamba and Cobra is potently neurotoxic and may cause difficulty with breathing within half an hour. Symptoms include a numbness of the lips, slurred speech, ptosis and progressive weakness. Antivenom is effective but often required in large quantities (10 – 15 vials).
  • A predominantly hemotoxic snake bite (eg Boomslang or tree snake) usually causes, initially, little or no swelling and very little pain. The bite is followed by oozing of blood from the bite site after a few hours, headache, mental confusion, nausea, vomiting and increased sweating. After several hours there may be bleeding from small cuts, the mucous membranes of the mouth and nose, and eventually severe internal bleeding which results in vomiting of blood and haemorrhage from the bowels. Kidney failure and brain haemorrhage may occur after a few days. 
  • If a victim is more than an hour or two from the closest medical facility, consider applying pressure bandages and splint to the affected limb, but only in suspected mamba or cobra bites. The idea is not to slow down blood flow, but rather to put pressure on the lymphatic system and, in doing so, reduce the rate at which venom is absorbed. After applying the pressure bandage, check for the presence of a pulse below distal to the bandage. Check the pulse every 10-15 minutes. If the pulse is not palpable, then the pressure bandage should be removed and the need for it reassessed.
  • In serious snakebite cases involving snakes with predominantly neurotoxic venom, like the Black Mamba, the victim may experience difficulty with breathing that warrant life-saving assisted breathing-mouth-to- mouth resuscitation and a bag valve mask-while in transit to the hospital.
  • Venom in the eyes (from spitting cobra) is very painful and must be flushed or diluted as quickly as possible with a weak (normal) saline solution, or a slowly running tap water for at least 15-20 minutes before seeking medical assistance. If no saline or water is available, other bland liquids like milk or even urine can be used.
  • Antivenom contains antibodies that neutralize venom’s toxic effects. The effectiveness of antivenom depends on how soon it is given; it is more effective when it is given within a short time after a snakebite.
  • Antivenom is manufactured mainly from horse blood. Up to 40% of adults and 60% of children will experience an allergic reaction to the antivenom. In some instances the reaction may be life-threatening like anaphylaxis.
  • Although some manufacturers advise use of an intradermal skin test to predict an acute reaction to antivenom, this procedure is terribly unreliable and only serves to waste precious time.  Such recommendations for skin testing should be ignored.
  • Before antivenin administration, intravascular volume should be expanded using crystalloids such as normal saline or Ringer’s lactate unless some contraindication (eg, congestive heart failure) is present. Pretreatment with antihistamines (H1 and H2 blockers) can be considered, though their efficacy at preventing adverse reactions to antivenom is unproven. Epinephrine should be immediately available for treatment of an anaphylactoid response.
  • Even after administering sufficient antivenom to bind all circulating venom, recovery may be delayed as many clinical and laboratory effects of venom are not immediately reversible.
  • Cholinesterase inhibitors (eg edrophonium , neostigmine) may be effective in temporarily reversing muscle weakness (eg, ptosis) until antivenom can be obtained. Neostigmine is can be used if a trial of short-acting edrophonium is effective.
  • Even bites that are from a nonvenomous snake or are dry need to be evaluated as they can lead to significant tissue damage or infections. Wash the bite with soap and water and cover the bite with a clean, dry dressing.

        In case of a snake bite Do NOT do any of the following: 

  • Do not pick up the snake or try to trap it.
  • Do not wait for symptoms to appear if bitten, rather seek immediate medical attention.
  • Do not apply a tourniquet.
  • Do not slash the wound with a knife.
  • Do not suck out the venom.
  • Do not apply ice or immerse the wound in water.
  • Do not drink alcohol as a painkiller or take any other drug unless adviced by a health professional.
  • Do not drink caffeinated beverages.


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