Fact 1: Epinephrine is the first-line treatment for anaphylaxis and should be administered immediately upon diagnosis.

Related Key Facts:

• Epinephrine can be repeated every 5-15 minutes if symptoms persist or worsen.
• The alpha-1 effects of epinephrine reverse peripheral vasodilation and reduce mucosal edema.
• Beta-1 effects increase myocardial contractility and heart rate, while beta-2 effects cause bronchodilation.
• Epinephrine's onset of action is within minutes when given intramuscularly.
• For patients in anaphylactic shock refractory to repeated IM epinephrine and fluids, consider continuous IV epinephrine infusion 1:1,000,000 (1 mcg/mL) via central venous access.

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Fact 2: Anaphylaxis can present without skin or mucosal involvement in up to 20% of cases.

Related Key Facts:

• Anaphylaxis is highly likely when there's acute onset of illness with involvement of skin/mucosa AND either respiratory compromise or reduced BP/end-organ dysfunction.
• Reduced BP alone (SBP <90 mmHg or >30% decrease from baseline) is sufficient to diagnose anaphylaxis if exposure to a known allergen has occurred.
• Lower respiratory tract symptoms (bronchospasm, wheezing) are more common than upper airway obstruction in anaphylaxis.
• Gastrointestinal symptoms (cramping, vomiting, diarrhea) can occur in up to 45% of anaphylaxis cases.
• Cardiovascular symptoms may be the primary manifestation in older adults or those with cardiovascular disease.

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Fact 3: Risk factors for severe or fatal anaphylaxis include asthma, cardiovascular disease, and mast cell disorders.

Related Key Facts:

• Patients with asthma are at higher risk for fatal anaphylaxis, particularly if their asthma is poorly controlled.
• Cardiovascular disease increases the risk of severe anaphylaxis due to reduced compensatory capacity.
• Mast cell disorders, including mastocytosis and mast cell activation syndrome, can cause unpredictable and severe anaphylactic reactions.
• Patients on ACE inhibitors may be at increased risk for more severe anaphylaxis and may be less responsive to treatment.
• Age-related factors, such as decreased organ reserve in elderly patients, can contribute to increased anaphylaxis severity.

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Fact 4: Biphasic anaphylaxis, characterized by recurrence of symptoms after initial resolution, can occur in up to 20% of cases within 72 hours.

Related Key Facts:

• Risk factors for biphasic reactions include severe initial reactions, delayed administration of epinephrine, and requirement for large doses of epinephrine.
• The median time to onset of biphasic reactions is 11 hours, but they can occur up to 72 hours after the initial reaction.
• Biphasic reactions can be more severe than the initial reaction and may be refractory to treatment.
• All patients should be prescribed an epinephrine auto-injector and educated on its use before discharge.
• Patients should be instructed to return immediately if symptoms recur and to wear medical alert identification.

Fact 5: Food, medications, and insect stings are the most common triggers of anaphylaxis, but idiopathic anaphylaxis accounts for up to 20% of cases.

Related Key Facts:

• Common food triggers include peanuts, tree nuts, shellfish, fish, eggs, milk, and soy.
• Medication triggers often include antibiotics (especially beta-lactams), NSAIDs, and neuromuscular blocking agents used in anesthesia.
• Hymenoptera (bee, wasp, hornet, yellow jacket, fire ant) stings are the most common insect triggers.
• The prevalence of specific triggers varies with age and geography.
• Patients with idiopathic anaphylaxis often require long-term prophylactic treatment with antihistamines and/or corticosteroids.

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Fact 6: Serum tryptase levels can help confirm the diagnosis of anaphylaxis, especially in unclear cases.

Related Key Facts:

• Tryptase is a protease released from mast cells during anaphylaxis.
• A tryptase level >11.4 ng/mL or an increase of >2 ng/mL over baseline strongly supports the diagnosis of anaphylaxis.
• Tryptase levels typically peak 1-2 hours after symptom onset and can remain elevated for up to 6 hours.
• Serial tryptase measurements can be more informative than a single measurement.
• Tryptase levels may not be elevated in food-induced anaphylaxis, despite severe symptoms.

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Fact 7: Long-term management of patients with anaphylaxis includes prescription of epinephrine auto-injectors, education on avoidance strategies, and consideration of immunotherapy for certain triggers.

Related Key Facts:

• Patients should be instructed to always carry two epinephrine auto-injectors and to use them at the first sign of anaphylaxis.
• Allergen avoidance strategies should be tailored to the specific trigger and may include reading food labels, communicating with restaurant staff, and avoiding high-risk situations.
• Venom immunotherapy can reduce the risk of future anaphylaxis by up to 95% in patients with insect sting allergies.
• Food oral immunotherapy is an emerging treatment for certain food allergies but is not yet widely available and carries risks.
• All patients with a history of anaphylaxis should wear medical alert identification and be referred to an allergist/immunologist for follow-up car