Acute Urticaria
Evaluation
Exhaustive work-up not indicated if no red flags are present [1, 4, 5]
- Evaluation by an Allergy/Immunology specialist is focused on finding a cause
through history, physical exam, and targeted testing when indicated
- Angioedema without urticaria: should prompt urgent referral to allergy immunology
o Consider bradykinin-mediated angioedema (hereditary/acquired)
o Medications: may stop ACEI (ACEI-related angioedema can occur at any
time during treatment, even years after initiation [27]) and possibly renin
inhibitors [28], ARBs (conflicting evidence – thought to be much lower risk
vs ACEI [28-30]), sacubitril, DPPV-4 inhibitors [31, 32]- History:
o Symptomatology:
▪ Rash description: lesion appearance, duration, photodocumentation;
the term “hives” is often used indiscriminately
▪ Urticaria distribution: localized or generalized
▪ Angioedema: present (concordant with or separate from hives) or
absent
▪ Concomitant symptoms: angioedema, rhinorrhea, sneezing, nasal
congestion, nausea, emesis, diarrhea, shortness of breath, wheezing,
stridor, voice changes, chest or throat tightness, palpitations, feeling
dizzy/lightheaded, (pre)syncope, sense of impending doom, uterine
cramps, change in behavior (especially relevant for pediatrics),
tachycardia, hypotension
▪ What were they doing at the time and in the few hours before onset
• Dietary and environmental exposures
• Exercise
▪ Review any previous episodes of urticaria
• Common triggers
• Cyclical pattern
▪ Systemic symptoms: fever, chills, nightsweats, unintentional weight
loss, arthritis, arthralgias, myalgias, hematuria, hematochezia, melena
• History of asthma or cystic fibrosis (ABPA)
• Presence and degree of control of other atopic conditions
o Travel
o Recent illnesses
o Change in medications, OTC vitamins/minerals or other supplements, topicals
o Recent vaccines
- Testing
o Skin and serum specific IgE (ssIgE) testing for suspected foods
o Skin testing and possibly oral challenge for medications, vaccines, excipients
o Testing for physical urticarias is feasible, though the sensitivity and specificity
of these tests are not well defined [1, 21]
o Lab testing: guided by history and physical; in general, if there are no red
flags or obvious triggers necessitating identification per history or exam,
testing is not recommended [1, 4, 22, 23]
▪ Consider: CBC with differential, CMP, ssIgE, stool studies, parasite
serology, UA, ESR, CRP, CH50, AH50, C3, C4, C1q
o Biopsy if indicated (systemic symptoms, end-organ involvement, prolonged
lesion duration and/or residual scar/bruise/dyspigmentation)