Evaluation of Sudden Onset Generalized Flushing

Immediate Assessment: Rule Out Anaphylaxis

• The American Academy of Allergy, Asthma, and Immunology recommends that the evaluation of sudden onset generalized flushing must immediately prioritize ruling out anaphylaxis, which is a life-threatening emergency requiring urgent epinephrine administration, followed by systematic exclusion of serious endocrine and neoplastic causes including carcinoid syndrome, pheochromocytoma, and mastocytosis 1, 2
• Anaphylaxis is highly likely if ANY ONE of the following criteria is present: acute onset with skin/mucosal involvement plus either respiratory compromise or reduced blood pressure, or two or more organ systems involved rapidly after allergen exposure, or reduced blood pressure after known allergen exposure 1, 2, 3, 4
• The American Academy of Pediatrics recommends administering epinephrine 0.3 mg intramuscularly immediately into the mid-outer thigh if anaphylaxis is suspected 3
• Delayed epinephrine is associated with increased mortality and poor outcomes including hypoxic-ischemic encephalopathy 3

Systematic Evaluation for Non-Anaphylactic Flushing

• The Annals of Oncology suggests obtaining serum tryptase levels 15 minutes to 3 hours after symptom onset and plasma histamine rises within 5 minutes and remains elevated for 15-60 minutes to evaluate for anaphylaxis 6, 7, 8
• Normal tryptase or histamine levels do NOT rule out anaphylaxis 7
• The American Journal of Hematology recommends grading severity for infusion-related reactions, with Grade 1 being mild, Grade 2 being moderate, Grade 3 being severe, and Grade 4 being life-threatening 6, 10
• The management of infusion reactions includes stopping the infusion immediately, monitoring vital signs, and administering hydrocortisone and famotidine for moderate reactions, and epinephrine for severe reactions 10

Common Pitfalls to Avoid

• Do not delay epinephrine if anaphylaxis criteria are met while waiting for laboratory confirmation, as recommended by the American Academy of Pediatrics 3
• Do not rely solely on tryptase or histamine levels to rule out anaphylaxis, as stated in the Annals of Oncology 7
• Do not overlook medication-induced flushing, which is far more common than neoplastic causes, as noted in Praxis Medical Insights 5, 9