Prevention of Future Allergic Transfusion Reactions After Generalized Itching
For patients who develop generalized itching (urticaria) after blood transfusion, antihistamine premedication should be considered for future transfusions only after a documented reaction, while routine premedication for all patients is not recommended due to lack of efficacy and potential to mask serious reactions. 1
Evidence Against Routine Premedication
The Association of Anaesthetists explicitly recommends against indiscriminate use of antihistamines and steroids for transfusion prophylaxis 1. This recommendation is based on:
Lack of proven efficacy: A systematic review and meta-analysis found no significant differences in transfusion reaction rates (including pruritis and rash) between patients who received anti-allergic premedication versus those who did not 2
Risk of masking serious reactions: Premedication can delay recognition of life-threatening complications such as hemolytic reactions or bacterial contamination, which require immediate intervention 1
Potential harm in immunocompromised patients: Repeated steroid doses can further suppress immunity in already vulnerable patients 1
Recommended Prevention Strategy for Your Patient
Since your patient has already experienced an allergic reaction (generalized itching), the approach differs from routine practice:
For Future Transfusions:
Antihistamine premedication is reasonable for this patient given their documented prior reaction 1. The American Journal of Hematology specifically recommends considering antihistamine premedication for patients with prior allergic transfusion reactions 1.
Use second-generation antihistamines when possible (such as loratadine 10 mg orally or cetirizine 10 mg IV/oral) rather than first-generation antihistamines like diphenhydramine 3. First-generation antihistamines should be avoided as they can cause sedation and potentially exacerbate hypotension 3.
Reserve corticosteroids for moderate-to-severe reactions only, not for simple urticaria 1.
Alternative Approach: Washed Blood Products
If antihistamine premedication fails to prevent recurrent reactions:
Washed blood products (particularly washed platelets or red blood cells) can be effective for preventing allergic transfusion reactions 4, 5. This removes plasma proteins that may trigger allergic responses, though some platelet loss occurs during washing 5.
Critical Monitoring Protocol
Regardless of premedication use, vigilant monitoring is essential 1:
- Document vital signs before, during, and after transfusion 1
- Monitor continuously for respiratory rate changes 1
- Watch for early warning signs including dyspnea and tachypnea 1
- Ensure immediate availability of emergency medications 1
Important Caveat: Food Allergies
Ask specifically about food allergies before future transfusions 4. Donor-derived food allergens (particularly from carrots, celery, nuts) can be transferred through blood products and cause reactions in sensitized recipients 4. If your patient has multiple food allergies, this significantly increases risk and may warrant washed blood products from the start 4.