Mild or Moderate Reaction during Infusion

  1. Stop the infusion and manage mild or moderate reactions (e.g. nausea, vomiting, urticaria, pruritus, chills, fever, etc) symptomatically as needed with antiemetics, antihistamines, steroids, etc.
  2. Reassess the patient once the reaction has been controlled; if the antivenom treatment criteria for cytotoxic, hemotoxic, or neurotoxic syndromes have not resolved completely then resume the infusion at a slower rate over 30 minutes.
  3. If giving via push, dilute the remaining dose of antivenom in a 100 - 500 mL bag of normal saline and give as 30-minute infusion.

Severe Reaction (Anaphylaxis) during Infusion

  1. Stop the infusion and treat according to the anaphylaxis treatment protocol. Reassess the patient once the reaction has been controlled; if the antivenom treatment criteria for cytotoxic, hemotoxic, or neurotoxic syndromes have not resolved completely then resume the infusion at a slower rate over 30 minutes.
  2. If giving via push, dilute the remaining dose of antivenom in a 100-250 mL bag of normal saline and give as 30-minute infusion.
  3. If the reaction occurs, stop the infusion and consult a physician expert via telemedicine to discuss next steps for management.

Anaphylaxis Treatment Protocol

NOTE: Intubate for airway edema not rapidly responsive to epinephrine.

If anaphylaxis occurs after antivenom administration, treat according to the following protocol:

1. First line treatment of anaphylaxis is rapid administration of 1:1000 epinephrine (initial adult dose = 0.5 mg IM in the lateral thigh for rapid absorption). Epinephrine can be repeated as needed until the patient has stabilized and/or an intravenous or intraosseous infusion administered as per standard protocols if the patient fails to respond to IM doses.

Epinephrine should always be given prior to antihistamines or steroids to counter the immediate life-threats of bronchospasm and vasodilation.

2. After epinephrine has been given:

  • Give methylprednisolone 125 mg IV
  • Give diphenhydramine 50 mg IV.
  • Consider adding an H2 antihistamine such as ranitidine.

If anaphylaxis occurs during administration of antivenom, stop the antivenom administration to treat the reaction, then resume the antivenom administration as described below. 15,61,95,99,128,129,140–146

Late Reactions to Antivenom (Serum Sickness)

  1. Serum sickness is characterized by flu-like symptoms ± rash that typically develops between 1 - 3 weeks after antivenom administration. Serum sickness may be uncomfortable but it is not dangerous.
  2. Serum sickness may be uncomfortable but it is not dangerous.
  3. Management is either symptomatic with antihistamines, acetaminophen, etc or with a course of oral steroids for patients who are in significant discomfort.94,95,97–99