What is the management for delayed urticaria (hives) after anesthesia?

Management of Delayed Urticaria After Anesthesia

For isolated delayed hives after anesthesia without systemic symptoms, administer chlorphenamine 10 mg IV (adult dose) and observe closely for progression to anaphylaxis. 1, 2

Immediate Assessment and Severity Classification

When a patient develops hives after anesthesia, your first priority is determining whether this represents isolated cutaneous involvement or evolving anaphylaxis:

• Isolated urticaria alone (without hypotension, bronchospasm, or angioedema) represents a less severe Grade I reaction that requires close observation but not epinephrine 2
• Urticaria plus any systemic symptoms (hypotension, bronchospasm, angioedema, cardiovascular collapse) indicates anaphylaxis requiring immediate epinephrine 2
• Be aware that cutaneous signs are absent in 28% of allergic anaphylaxis cases, so lack of hives does not exclude anaphylaxis 1

Critical Timing Considerations

Delayed reactions are particularly associated with specific agents:

• Symptoms may be delayed up to one hour with latex, antibiotics, IV colloids (hydroxyethyl starch, dextran), or surgical instrument disinfectants (Cidex OPA) 1, 2
• Even with delayed presentation, these substances can still cause immediate-type reactions, so timing alone does not exclude them 1

Treatment Protocol Based on Severity

For Isolated Urticaria (Grade I Reaction)

Primary treatment:

• Administer chlorphenamine (H1-antihistamine) 10 mg IV or IM slowly for adults 1, 2
• Pediatric dosing: 5 mg (6-12 years), 2.5 mg (6 months-6 years), 250 µg/kg (<6 months) 2
• Do NOT administer epinephrine for isolated cutaneous signs without systemic involvement 2

Secondary treatment for persistent symptoms:

• Consider hydrocortisone 200 mg IV for adults with moderate or persistent symptoms 1, 2
• This is particularly useful if symptoms do not resolve within 15 minutes 1

For Urticaria with Systemic Symptoms (Anaphylaxis)

If hives are accompanied by hypotension, bronchospasm, or angioedema, this is anaphylaxis requiring:

• Epinephrine 50 µg IV (0.5 ml of 1:10,000 solution) as initial adult dose, with repeat doses as needed 1
• Maintain airway, administer 100% oxygen, elevate legs if hypotensive 1
• Aggressive fluid resuscitation with saline 0.9% or lactated Ringer's solution 1
• Chlorphenamine 10 mg IV and hydrocortisone 200 mg IV as adjunctive therapy 1

Critical Pitfalls to Avoid

Recognizing Atypical Presentations

• Isolated hypotension occurs in 10% of anaphylaxis cases and may be the only sign, especially with neuraxial blockade—do not dismiss hypotension without cutaneous signs 1, 2
• Bradycardia (not tachycardia) occurs in approximately 10% of allergic anaphylaxis during anesthesia 1, 2
• Surgical drapes may obscure skin symptoms, making diagnosis more challenging 3

Medication Considerations

• Avoid first-generation antihistamines (diphenhydramine) as they can exacerbate hypotension, cause sedation, and convert minor reactions into serious adverse events 1
• Second-generation antihistamines (loratadine 10 mg PO, cetirizine 10 mg IV/PO) are preferred if additional antihistamine therapy is needed 1

Mandatory Post-Reaction Management

Documentation Requirements

Every patient with widespread urticaria or suspected anaphylaxis requires:

• Immediate referral to a specialist Allergy/Immunology center 1, 2
• Provide a legible copy of the anesthetic record and recovery room chart 2
• Document all drugs administered before symptom onset, including timing 1

Diagnostic Testing

• Collect blood samples for serum tryptase immediately after the event and obtain a baseline sample 24 hours later 1
• Skin testing should be performed after the patient has fully recovered clinically and antihistamine effects have worn off 2
• The most common causative agents in order of frequency are: neuromuscular blocking agents, natural rubber latex, hypnotic induction agents, antibiotics, and IV colloids 2, 4

Patient Education and Follow-up

• Warn patients that recurrent urticaria may occur over the next 1-2 days even after stopping the causative agent—this is expected and does not indicate treatment failure 5
• Document the suspected allergy prominently in the medical record 5
• For future anesthetics, all exposures before the reaction should be avoided until allergy testing is complete 1

Special Considerations for Future Anesthesia

If the patient requires surgery before allergy investigation is complete:

• For emergency surgery: Use regional or inhalational anesthetic techniques to minimize IV drug exposures 1
• Avoid latex, chlorhexidine, neuromuscular blocking agents, and penicillin/cephalosporin antibiotics if possible 1
• Patients with latex allergy may cross-react with certain fruits 2
• History of cutaneous sensitivity to cosmetics or quaternary ammonium compounds raises caution for muscle relaxant reactions 1, 2