D2.400 - Vitamin Hypersensitivity in the Era of Intravenous ‘Cocktails’: Diagnostic Pitfalls and Clinical Consequences

Evidence on hypersensitivity reactions (HSRs) to vitamin preparations is limited, particularly with respect to reactions following mixed intravenous treatments. This study aimed to characterize HSRs related to vitamin preparations and to evaluate the role of diagnostic testing.

A total of 219 patients with suspected HSRs to vitamin preparations between 2000 and 2025 were analyzed.Reaction severity was graded according to the World Allergy Organization anaphylaxis system.Skin tests (STs) were performed with vitamin preparations in mixed intravenous treatments, and concomitant non-vitamin drugs. Basophil degranulation(BDTs) and drug provocation(DPTs) tests were performed in selected patients.

The median age was 37 years(IQR:28–44), and 82.6% of the patients were female.Reactions occurred within the first hour in 86.7% of the cases and were most commonly associated with intravenous administration.Anaphylaxis was observed in 154 patients and was more frequent in reactions related to mixed intravenous treatments(p<0.001).The median baseline serum tryptase levels was 3.53ng/mL(IQR:2.41–4.54).Intravenous administration and a history of drug allergy were independently associated with anaphylaxis[p=0.018,OR(CI95%):0.28(0.10–0.81);p=0.024,OR(CI95%):0.46(0.24–0.90)].

Among patients who reacted to mixed intravenous treatments(n=155), ST positivity was observed for non-vitamin drugs in 22 patients and vitamin preparations in 12 patients, with two additional patients showing positive BDT results.ST positivity was detected in five patients who reacted to single-vitamin preparations(n=64).ST positivity was independently associated with anaphylaxis[p=0.017,OR(CI95%):4.50(1.31–15.50)] and mixed intravenous treatments[p=0.030,OR(CI95%):3.38(1.12–10.17)].

DPTs with suspected culprit vitamin preparations were performed in 71 cases and were positive in three patients, whereas provocation with 21 alternative drugs was tolerated without adverse reactions.Overall, diagnostic test positivity was observed in 19(8.67%) patients with suspected vitamin hypersensitivity.

Our findings highlight the potential risks associated with the widespread use of mixed intravenous treatments. Particularly parenteral administration and previous drug allergy history can be associated with more severe reactions. Diagnostic testing is essential to prevent mislabeling as vitamin allergy and to distinguish true vitamin hypersensitivity from reactions related to non-vitamin components or excipients in mixed preparations.