Association of Acid-Suppressive Medication and Antimicrobial Use in Infancy with Food Allergy and Anaphylaxis

<b>Background/Objectives:</b> The incidence of food allergies and other allergic diseases is rising. Emerging evidence links both antimicrobials and acid-suppressive therapy with gut dysbiosis, which is implicated in allergy development. We investigated the relationship between the use of acid-suppressive medications or antimicrobials in infancy and the risk of developing childhood allergic diseases. <b>Methods:</b> The US network in the TriNetX platform was used to identify patients prescribed proton pump inhibitors (PPIs), histamine-2 receptor antagonists (H₂RAs), antimicrobials ≥1, or antimicrobials ≥3 times during their first year of life from October 2015 to January 2022. ICD-10 diagnoses were used to assess two-year outcomes of anaphylaxis, food allergy, and atopic dermatitis. A sub-analysis in gastroesophageal reflux (GERD) patients was also performed. <b>Results:</b> Risks of anaphylaxis and food allergy increased with the prescription of PPIs (risk ratio [95% CI], 2.49 [1.40-4.41], 5.33 [4.97-5.71]), H₂RAs (4.48 [3.43-5.86], 4.21 [4.01-4.41]), and antimicrobials ≥1 (2.41 [2.13-2.72], 1.90 [1.86-1.94]), or ≥3 times (3.69 [3.12-4.37], 2.79 [2.70-2.88]). Risk of atopic dermatitis was increased in both H₂RA (1.41 [1.35-1.48]) and antimicrobial groups (2.25 [2.22-2.28], 3.35 [3.29-3.41]), but not in the PPI group. In the GERD sub-analysis, anaphylaxis risk was not significantly different, food allergy risk was increased in both PPI (2.30 [2.08-2.53]) and H₂RA groups (1.77 [1.63-1.92]), and atopic dermatitis decreased in the PPI group (0.76 [0.67-0.85]) but slightly increased in the H₂RA group (1.11 [1.03-1.20]). <b>Conclusions:</b> Exposure to acid-suppressive or antimicrobial medications during infancy was associated with increased risk of food allergy and anaphylaxis in early childhood. In infants diagnosed with GERD, exposure to acid-suppressive medications was still associated with increased food allergy risk.