Medications, IV Contrasts Increase Anaphylaxis Odds in Older Adults

A new study identified factors that increased the odds of anaphylaxis among older adults at emergency department visits, such as medications and intravenous (IV) contrast.1

Limited research focuses on anaphylaxis characteristics and outcomes in older adults. According to the KeepSmilin4Abbie Foundation, older adults may not experience the typical anaphylaxis symptoms of skin rash, difficulty breathing, and nausea. Rather, they may experience chest pain, confusion, and fainting.2 A heart attack or a stroke can mask these symptoms, delaying the treatment of the life-threatening anaphylaxis.

An analysis published in 2023 identified several trends among adults with anaphylaxis, including increasing age linked to more severe presentations.3 The study examined participants (mean age: 31 years) who visited St. Vincent’s Hospital in Sydney, Australia, with anaphylactic presentations from January 2009 to December 2018. Investigators discovered individuals over 65 years were more likely to have identifiable triggers for anaphylaxis than younger individuals (< 65 years), with medications being the most prominent trigger in this age group (75% vs 20.1%).

Another study also showed that medication was the most frequent anaphylaxis trigger in older adults (P = .039), which was more common than in younger adults.4 Cardiovascular symptoms were seen more in older adults experiencing anaphylaxis than in younger adults. Hospital rates and adrenaline administration were also more frequent in older adults than younger adults (P = .001).

Food was a common trigger in older adults, but more common among younger adults, and respiratory symptoms were significantly less common in older adults. Skin was the most affected organ in older and younger adults but was less affected in older adults.

Investigators, led by Marie-Joy Nduwimana, from the department of emergency medicine at Mayo Clinic, conducted a cohort study to expand on this previous research and learn more about how the presentation of anaphylaxis differed in older adults (≥ 65 years) compared with younger adults (aged 18 – 64 years).1 They compared triggers, presentation, management, and outcomes of anaphylaxis emergency department visits in older and younger adults. The team analyzed data from both the pre-hospital setting and the emergency department.

The study included adults who met the anaphylaxis criteria from April 2008 to December 2022. Among 1422 visits, 212 (14.9%) were for older adults. The team analyzed visit characteristics and outcomes by age group using chi-squared analysis and multivariable logistic regression.

Compared with younger adults, anaphylaxis among older adults was more likely to be triggered by medications (34.0% vs 21.3%; odds ratio [OR] 1.85; 95% confidence interval [CI], 1.34 – 2.55) and IV contrast (13.2% vs 5.6%; OR 2.50; 95% CI, 1.55 – 4.04). Older adults also had increased odds of severe anaphylaxis (adjusted OR [aOR], 1.57; 95% CI, 1.12 – 2.21), requiring endotracheal intubation (aOR, 6.24; 95% CI, 2.69 – 14.48) and hospital or intensive care unit (ICU) admission (aOR, 1.78; 95% CI, 1.19 – 2.67).

The study also showed older adults were more likely to arrive via emergency medical services (EMS) (56.1% vs 34.0%; OR, 2.56; 95% CI, 1.89 – 3.46) but less likely to receive EMS-administered epinephrine (26.0% vs 32.4%; aOR, 0.46; 95% CI, 0.27 – 0.77).

“Visits among older adults had increased odds of anaphylaxis from medications and IV contrast, cardiovascular symptoms, and more severe outcomes, including intubation and ICU admission,” investigators concluded. “Improved EMS epinephrine administration and prehospital guidelines could enhance outcomes for older adults with anaphylaxis.”

References

1. Nduwimana MJ, Liu SW, Goldberg EM, Bellolio F, Mullan AF, Wilson R, Campbell RL. Characteristics and Outcomes of Anaphylaxis in Emergency Department Visits Among Older Adults. J Allergy Clin Immunol Pract. 2025 Apr 22:S2213-2198(25)00380-0. doi: 10.1016/j.jaip.2025.04.023. Epub ahead of print. PMID: 40274230.

2. Smith, T. Increasing Age Linked to More Severe Anaphylaxis, Medications Frequent Trigger for Older Adults. HCPLive. July 25, 2023. https://www.hcplive.com/view/increasing-age-linked-more-severe-anaphylaxis-medications-frequent-trigger-for-older-adults. Accessed May 8, 2025.

3. Anaphylaxis and Aging: Crucial Facts Everyone Needs To Know. The KeepSmilin4Abbie Foundation. https://keepsmilin4abbie.org/anaphylaxis-and-aging-crucial-facts-everyone-needs-to-know/. Accessed May 8, 2025.

4. Yıldız E, Arslan Ş, Çölkesen F, Evcen R, Sadi Aykan F, Kılınç M. Anaphylaxis in older adult patients: a 10-year retrospective experience. World Allergy Organ J. 2022 Jul 14;15(7):100665. doi: 10.1016/j.waojou.2022.100665. PMID: 35891674; PMCID: PMC9293944.