The severity of the clinical syndrome following a black widow spider (genus Latrodectus) can be graded based on the extent of the patient’s signs and symptoms.
Grade 1:
(1) asymptomatic
(2) local pain at envenomation site
(3) normal vital signs
Grade 2:
(1) muscular pain in extremity envenomated
(2) extension of muscular pain to abdomen if envenomated on lower extremity or chest if envenomated on upper extremity
(3) local diaphoresis (perspiration) of envenomation site or involved extremity
(4) normal vital signs
Grade 3:
(1) generalized muscular pain in back, abdomen and chest
(2) diaphoresis remote from envenomation
(3) nausea and vomiting
(4) headache
(5) tachycardia (pulse > 100 per minute)
(6) hypertension (systolic blood pressure > 140 mm Hg, and/or diastolic blood pressure > 90 mm Hg)
Signs and Symptoms
Grade 1
Grade 2
Grade 3
vital signs
normal
normal
hypertension
tachycardia
pain
+/- local pain
muscle pain in extremity; pain in abdomen if bit on leg; pain in chest if bit on arm
generalized muscle pain (chest, abdomen, back)
diaphoresis
none
at envenomation site and/or extremity
diaphoresis remote from envenomation site
systemic symptoms
none
none
nausea
vomiting
headache
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