Clinical Presentation
Anaphylaxis may include any combination of common signs and symptoms (Table 2). Cutaneous manifestations of anaphylaxis, including urticaria and angioedema, are by far the most common. The respiratory system is commonly involved, producing symptoms such as dyspnea, wheezing, and upper airway obstruction from edema. Gastrointestinal manifestations (e.g., nausea, vomiting, diarrhea, abdominal pain) and cardiovascular manifestations (e.g., dizziness, syncope, hypotension) affect about one third of patients. Headache, rhinitis, substernal pain, pruritus, and seizure occur less frequently.
Symptom onset varies widely but generally occurs within seconds or minutes of exposure. Rarely, anaphylaxis may be delayed for several hours. Anaphylaxis can be protracted, lasting for more than 24 hours, or recur after initial resolution.
TABLE 2
Frequency of Signs and Symptoms
|
Signs and symptoms
|
Frequency (%)
|
|
Urticaria, angioedema
|
88
|
|
Dyspnea, wheeze
|
47
|
|
Dizziness, syncope, hypotension
|
33
|
|
Nausea, vomiting, diarrhea, cramping abdominal pain
|
30
|
|
Flush
|
46
|
|
Upper airway edema
|
56
|
|
Headache
|
15
|
|
Rhinitis
|
16
|
|
Substernal pain
|
6
|
|
Pruritus without rash
|
4.5
|
|
Seizure
|
1.5
|
