Envenomation (Scorpions)

The protocol for Envenomation (Scorpions):



Let’s break it down!

The vast majority of scorpions are harmless. Out of approximately 1,750 species of scorpions, only about 25 of them are venomous to humans. Still, about 1.5 million scorpion stings occur annually resulting in over 3,000 deaths. Soldiers in austere environments are naturally at a high risk of encountering them.

Most scorpion stings are unintentional; scorpions are not inherently aggressive creatures as they would much rather run away from humans than try to attack. Stings usually occur when someone accidentally steps on the scorpion or reaches underneath a rock or crevice.  Stings may also occur in humans when they dress, get into bed, or when they are either lean or sit against walls

For a fun introduction, here’s a video of a man intentionally getting stung by a scorpion:

A sting from a scorpion can initially look like any other sting/bite from an organism: red, swollen, and painful. The interesting thing about scorpion envenomations though is that they can also follow on with a wide range of additional neurotoxic symptoms that sometimes contradict each other.  Since scorpion venom exerts a broad over-stimulation of neurons; both the sympathetic nervous system (“fight or flight“) AND the parasympathetic nervous system (“rest and digest“) can be activated at once.  Patients can experience opposing symptoms like hypertension or hypotension, tachycardia or bradycardia, etc.  Other unique symptoms include blurred vision, tongue fasciculations, and seizures.

Symptoms will generally occur within 15 minutes of the sting, if at all.  The following scorpion envenomation grading scale is commonly used in emergency departments:

  • Grade I: Pain or paresthesia at the sting site.
  • Grade II: Pain or paresthesia at the sting site and remote areas.
  • Grade III: Cranial nerve and autonomic dysfunction or somatic skeletal neuromuscular dysfunction.
    • Cranial nerve dysfunction includes blurred vision, opsoclonus, hypersalivation, tongue fasciculations, dysphagia, dysphonia, and upper airway abnormalities.
    • Somatic neuromuscular dysfunction includes restlessness and severe limb jerking.
  • Grade IV: Both cranial nerve and somatic neuromuscular dysfunction.

*Approximately 66%-90% of stings are limited to Grade I or Grade II, but it depends largely on the species of scorpions.  

The video below shows an excellent example of patients suffering from severe scorpion envenomation symptoms:

1. Treat per Pain Management protocol

Most stings are harmless and will only need analgesics to help cope with the pain.  NSAIDs and Tylenol are generally enough, but opiates like Morphine or Fentanyl could be used to manage the most severe cases.  Fentanyl may be more preferred because it causes less of a histamine release.

Amazon.com: Amazon Basic Care Acetaminophen Extended-Release ... Injured US Marines to get 'lollipop' instead of morphine - Telegraph

2. Treat per Nausea/Vomiting protocol

Nausea is not a particularly common symptom associated with scorpion stings but is likely to occur in those who experience the more severe, systemic envenomations.  Ondansetron or Promethazine would be your drugs of choice.

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3. Apply ice packs to bite site

This simply helps with the pain and inflammation caused by the sting; no remarkably curative effects.

How to Make Your Own Ice Packs and Heat Packs > Air Force Medical ...

4. Diphenhydramine (Benadryl) 25-50mg q6hr prn PO/IV

For the management of any potential allergic reactions, giving an antihistamine like diphenhydramine may be beneficial.  Anaphylaxis is not particularly common in scorpion envenomations, but minor localized allergic reactions may still occur.

Diphenhydramine Capsules 50mg 1000/Bottle

Scorpion stings are not usually life-threatening; most patients will be just fine without an evacuation so long as their symptoms are managed. Often it can be difficult to distinguish scorpion stings from spider bites, which can be more problematic if it comes from a brown recluse that is capable of causing tissue necrosis.  These cases will require at least a Routine evacuation.  Of course, anybody with signs/symptoms of anaphylaxis or severe envenomation should have an Urgent evacuation to a hospital that carries stocks of antivenom


Good luck out there!



Brandon Simpson, PA-C
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