Mechanisms of NSAID-induced anaphylaxis are unknown in most cases, though accelerated IgE formation is supposed for aril-propionic agents (ibuprofen, ketoprofen, flurbiprofen, naproxen, fenoprofen, oxaprozin, aceclofenac, and fenclofenac) and transient competitive inhibition of prostanoid biosynthesis may also contribute to symptoms [42]. This evidence concerns the gene IGHE and anaphylaxis.