Risk of systemic reactions with large local reactions
Question:
12/5/2024
I have a 6 (almost 7)-year-old boy that continues to have large local reactions to allergy shots, slightly larger than a half dollar. These reactions start around 4 hours after the injection has been given. Mom has showed me pictures of them, and there is significant erythema. However, they do not seem to be causing significant impairment in activity or sleep. We have tried cutting the dose in the 1:1 vial and the reactions have persisted. Also, mom is concerned that allergies, while they have improved on the immunotherapy course, are still causing some asthma flares. I am considering going up on the volume in the 1:1 vial despite the reactions to try to get better control of allergies. Should I have any concern about increasing the risk of a systemic reaction, or any other concern about increasing the dose of the immunotherapy given these large local reactions?
Answer:
For your patient, given the lack of causative association with the risk of systemic subsequent risk of systemic reactions after large local reactions, I would not have concern about increasing the dose of environmental allergen immunotherapy.
The safety of subcutaneous immunotherapy (SCIT) has been determined through a national survey of allergists in North America between 1990 and 2001 that estimated one fatal reaction occurred after every 2.5 million injection visits, averaging 3.4 fatal reactions per year. (James et al.2017) Risk factors for fatal reactions include uncontrolled asthma at the time of administration of injections, dosing errors, delay or inadequate administration of epinephrine during anaphylaxis, a prior history of injection-related systemic reactions, and administration of injections during peak allergy seasons.
Large local reactions (LLRs) are defined as pruritus and/or erythema (>2.5 cm) at the site of injection and up to 26–86% of patients receiving SCIT experience local reactions . Roy et al. reported patients with a history of systemic reactions had a rate of systemic reactions that was four-fold greater than those without a history of systemic reactions, and one-third of these systemic reactions had been preceded by LLRs. Although conflicting data exist on risks of prior LLRs, practice guidelines recommend that there is generally no need for dose adjustment of SCIT, as such adjustments have not demonstrated significant reduction in the risk of subsequent systemic reactions. (Prigal SJ 1972, Kelso JM 2004, Cox L 2011) Nevertheless, it is reasonable to repeat or adjust the dose for individual patients considered to be at greater risk for a systemic reaction.
Based on the above information, ensure your patient’s asthma is well controlled at the time of the allergy shot. Updosing is a reasonable plan even with LLRs.
References
James C, Bernstein DI. Allergen immunotherapy: an updated review of safety. Curr Opin Allergy Clin Immunol. 2017 Feb;17(1):55-59. doi: 10.1097/ACI.0000000000000335. PMID: 27906697; PMCID: PMC5644500.
Roy SR, Sigmon JR, Olivier J, et al. Increased frequency of large local reactions among systemic reactors during subcutaneous allergen immunotherapy. Ann Allergy Asthma Immunol. 2007; 99:82–86. [PubMed: 17650835
Prigal SJ. A ten-year study of repository injections of allergens: local reactions and their management. Ann Allergy. 1972; 30:529–535. [PubMed: 5056915]
Kelso JM. The rate of systemic reactions to immunotherapy injections is the same whether or not the dose is reduced after a local reaction. Ann Allergy Asthma Immunol. 2004; 92:225–227. [PubMed: 14989390]
Cox L, Nelson H, Lockey R, et al. Allergen immunotherapy: a practice parameter third update. J Allergy Clin Immunol. 2011; 127(1 Suppl):S1–S55. [PubMed: 21122901]
Carla M. Davis, MD, FAAAAI