How should itching and urticaria occurring during a blood transfusion be managed?

Management of Itching and Urticaria During Blood Transfusion

For mild to moderate allergic reactions (itching and urticaria without respiratory or cardiovascular compromise), immediately slow or temporarily stop the transfusion, administer intravenous antihistamines (diphenhydramine 50 mg IV plus ranitidine 50 mg IV), and once symptoms resolve, restart the transfusion at 50% of the original rate with close monitoring. 1

Initial Assessment and Immediate Actions

When itching and hives develop during blood transfusion, the critical first step is determining whether this represents a simple allergic reaction (Grade 1-2) versus anaphylaxis requiring aggressive intervention 1:

Distinguish Between Allergic Reaction and Anaphylaxis

Simple allergic reactions present with 1:

• Pruritus (itching)
• Urticaria (hives)
• Flushing
• No respiratory compromise
• No hypotension
• No angioedema

Anaphylaxis includes 1:

• Symptomatic bronchospasm
• Dyspnea or wheezing
• Hypotension
• Angioedema
• Life-threatening respiratory or cardiovascular compromise

Management Algorithm for Non-Anaphylactic Allergic Reactions

Grade 1 Reactions (Mild Symptoms)

For isolated itching without visible urticaria 1:

• Slow the infusion rate
• Continue monitoring vital signs every 15 minutes
• Document respiratory rate, pulse, blood pressure, and temperature 1
• Consider administering antihistamine if symptoms persist

Grade 2 Reactions (Moderate Urticaria with Itching)

This is the most common scenario requiring intervention 1:

1. Stop or slow the transfusion immediately 1
2. Maintain IV access with normal saline 1
3. Administer symptomatic treatment 1:
   • Diphenhydramine 50 mg IV (H1 antagonist)
   • Ranitidine 50 mg IV (H2 antagonist)
4. Monitor vital signs continuously until symptoms resolve 1
5. Once patient is stable and symptoms resolve 1:
   • Restart transfusion at 50% of the original infusion rate
   • Titrate to tolerance
   • Continue close monitoring

Important Clinical Considerations

Avoid Routine Corticosteroids

Do not use corticosteroids indiscriminately for simple allergic reactions 1. The 2025 Association of Anaesthetists guidelines specifically recommend against routine steroid use, as repeated doses may further suppress immunity in already immunocompromised patients 1. Reserve corticosteroids (methylprednisolone 1-2 mg/kg IV every 6 hours) for Grade 3-4 reactions or suspected anaphylaxis 1.

Product-Specific Patterns

Allergic reactions occur more commonly with 2, 3:

• Plasma-containing products (platelets, fresh frozen plasma)
• Red blood cells can also cause allergic reactions but less frequently than plasma products 3

Monitoring Requirements

Throughout the transfusion episode, document 1:

• Vital signs before transfusion (within 60 minutes)
• Vital signs at 15 minutes after starting each unit
• Vital signs within 60 minutes of completing transfusion
• Respiratory rate is particularly critical as dyspnea and tachypnea indicate serious reactions 1

When to Escalate Care

Grade 3-4 Reactions Require Aggressive Management

Stop the transfusion permanently if 1:

• Symptoms progress despite treatment
• Any signs of anaphylaxis develop (bronchospasm, hypotension, angioedema)
• Severe urticaria with systemic symptoms

For suspected anaphylaxis, immediately administer 1:

• Epinephrine 0.2-0.5 mg IM (1 mg/mL), repeat every 5-15 minutes as needed
• Normal saline 1-2 L IV infusion at 5-10 mL/kg in first 5 minutes
• H1/H2 antagonists: diphenhydramine 50 mg IV plus ranitidine 50 mg IV
• Corticosteroids: methylprednisolone 1-2 mg IV/kg every 6 hours

Prevention Strategies for Future Transfusions

For Patients with Prior Allergic Reactions

Consider premedication for subsequent transfusions 1, 3:

• Oral or IV antihistamine (diphenhydramine 25-50 mg or cetirizine 10 mg)
• Administer 30-60 minutes before transfusion
• Do not routinely premedicate all patients, only those with documented prior reactions 1

Washed Blood Products

For patients with recurrent allergic reactions 4:

• Washed red blood cells remove plasma proteins that trigger reactions
• Washed platelet concentrates are effective for preventing anaphylactoid reactions
• Consider for patients with documented anti-plasma protein antibodies 4

Post-Reaction Management

Observation Period

All patients with allergic reactions require 1:

• Minimum 6 hours of monitored observation from reaction onset
• Extended observation for severe reactions (Grade 3-4)
• Monitor for biphasic reactions, though risk is low with simple allergic reactions 1

Documentation and Reporting

Complete hemovigilance reporting 2, 5:

• Document reaction type, severity, and management
• Report to institutional transfusion service
• Ensure future transfusion orders include reaction history
• Consider allergy testing if recurrent or severe reactions occur

Common Pitfalls to Avoid

Do not automatically discard the blood product 3. Most non-severe allergic reactions (75% of cases) resolve with treatment and the transfusion can be completed, preventing unnecessary product wastage 3. Only 36% of patients with incomplete transfusions due to non-severe reactions required re-transfusion within 48 hours 3.

Do not use antihistamines as first-line treatment for anaphylaxis 1. Epinephrine is the only appropriate first-line treatment for anaphylaxis; antihistamines are adjunctive therapy only 1.

Do not assume all reactions are allergic 1. Febrile non-hemolytic reactions are also common and require different management (paracetamol only, not antihistamines) 1.