| | | Widow spiders: Serious bites are usually felt as a mild sting Local pain may develop within minutes or up to 10 hours later Pain may become severe, with or without local sweating, erythema, central blanching, or petechiaec Pain may extend proximally (for bites on extremities) or become regional, presenting as chest pain (mimicking angina), abdominal pain (mimicking acute abdomen), or head/neck pain (contorted facies latrodectisma) Hypertension Nausea Muscle spasms Untreated bites may result in leg pain and can be associated with profuse lower limb sweating (even with bites to the upper extremities) Pulmonary edema and generalized paralysis are rare Untreated major systemic envenomation can cause serious symptoms over two to five days, and up to weeks
Arizona bark scorpion: Burning pain (often severe) lasting minutes to days Pruritus, hyperesthesia, and faint erythema or edema Local paresthesia Peripheral neuroexcitatory effects (nonparalytic) Catecholamine effects (e.g., hyperexcitability, restlessness, coma, convulsions) Repetitive eye movements or nystagmus in children Tachycardia, tachypnea, mydriasis, and hypertension Bradycardia, hypotension, salivation, lacrimation, diarrhea, and gastric distention Muscle fasciculation Colicky abdominal pain and vomiting
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| Treatment |
| Wound care as indicated |
| Obtain IV access |
| Anaphylaxis protocol |
| General treatment considerations: |
| All patients with serious envenomations should be closely monitored; those with cardiovascular comorbidities should be monitored continuously. |
| Additional treatments may include nonsedating analgesia, benzodiazepines for muscle spasm, and tetanus prophylaxis. |
| After administration of antivenom, a short, nontapered course of prednisone (40 to 60 mg daily for five days) should be given to decrease the incidence of type III immune complex disease. |
| Ensure close follow-up after discharge for all patients with serious envenomations. |
| Widow spiders: |
| Antivenom indications include increasingly severe pain, proximal spread of muscle spasm, rigidity from bite site to abdomen and head, increased sweating, and hypertension. |
| Antivenom dosing and administration: |
| Administer 1 vial of antivenom (2.5 mL) diluted in 200 to 250 mL saline over two hours; additional vials may be titrated against persistent muscle spasm or pain; antivenom may be given up to one week after a serious envenomation.‡ |
| Patients should be counseled about the risks and benefits of antivenom therapy. |
| Arizona bark scorpion: |
| Antivenom indications: signs of systemic neurotoxicity; indications for local envenomation have not been established.§ |
| Antivenom dosing and administration are dependent on the product, as advised by a poison control center. |
| Patients should be counseled about the lack of FDA approval for this antivenom. |
| All patients with serious envenomation must be counseled about the risk of antivenom anaphylaxis, immune complex disease, and possible loss of function, regardless of treatment effectiveness. |
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| | No first aid recommendations Prompt evaluation by a physician is strongly advised Capture of spider (with strict safety precautions) is strongly advised
| Cutaneous loxoscelism: Local pain (moderate to severe) Erythema (may show clinically six to 24 hours after bite) Edema Mottled dark or hemorrhagic foci, with or without local blistering General symptoms (e.g., fever, malaise, rash) Lesion evolution over five to seven days (necrosis or ulceration, possible dry gray or blue-black eschar) Necrotic wound may extend over several weeks, with or without recurrent breakdown, pain, and ulceration Severe cases may have necrotic extension well beyond the dermis
Viscerocutaneous loxoscelism (uncommon to rare): Presentation similar to cutaneous loxoscelism, with potentially lethal systemic effects (e.g., hemolysis, thrombocytopenia, disseminated intravascular coagulation, secondary renal failure, shock)
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| Meticulous wound care is essential in patients with confirmed loxoscelism. |
| No antivenom is available in the United States, and no specific treatment (e.g., dapsone, early debridement) is supported by the evidence. Anecdotal reports of effectiveness of hyperbaric oxygen therapy are unproven. |
| Patients with confirmed loxoscelism should be counseled about potential chronic and complicated sequelae. |
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| | Remove stinger with forceps, if applicable (do not squeeze venom gland on end of stinger) Except for tarantula envenomations, briefly apply insulated ice pack to bite site (limit to 10 minutes per hour for three hours) Acceptable to give diphenhydramine (Benadryl) or desloratadine (Clarinex) Serious stings should be evaluated by a physician Obtain history of stings and atopic tendencies, watch for signs of anaphylaxis, and manage per protocol Persons with known atopy should receive epinephrine via preloaded syringe or in the emergency setting; emergent airway management may be indicated
| Local pain, erythema, and edema of variable severity Hyperreactive airway or anaphylaxis can occur if atopy to insect venoms is present
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| Airway, breathing, and circulation are first priority |
| Major concern is atopic response with the possibility of anaphylaxis; treatment is focused on thorough history, careful observation for escalating local or systemic reactions, and immediate availability of anaphylaxis protocol |
| Wound care |
| Severe pain can be managed with modest use of opioids (hydrocodone/acetaminophen) |
| Tetanus prophylaxis and follow-up |
| Secondary infections require broad-spectrum antibiotics |