IL4R rs1801275 AA, IL13 rs20541 GG, and IL-4 rs2243250 CC genotypes synergistically amplified allergy risk under vitamin D deficiency (adjusted OR = 26.14, p = 0.019; OR = 6.51, p = 0.025; OR = 4.13, p = 0.007). Here, IL4 is linked to vitamin D deficiency.