The abdominal pains are frequently most severe, mimicking appendicitis, colic, or food poisoning. Other symptoms include headache, restlessness, anxiety, fatigue, and insomnia. Slight erythema, piloerection locally, mild edema or urtication, local perspiration, and lymphangiitis are the primary local features that may be present. Laboratory evaluation is not helpful in diagnosis, although hemoglobinuria, albuminuria, and leukocytosis may be found. Nonspecific bites mainly show neutrophils during the early toxic response and a mononuclear infiltrate of lymphoid cells and plasma cells during the later allergic response.
Eosinophils are few to absent.
The outcome, even in untreated cases of black widow bites, generally is favorable with supportive care. Treatment centers on alleviating pain and muscle cramping. The 3 main treatments are pain relievers, such as narcotics, muscle relaxants, and intravenous calcium gluconate. A spider antivenin produced in horses is available for Latrodectus venom and appears efficacious no matter which Latrodectus species bit the victim. Since the possibility of anaphylaxis or serum sickness always exists, use antivenin only in those who are at high risk for severe complications.