However, it is—at present—the most likely explanation for immediate (<10 min), IgE mediated degranulation of mast cells by a drug-protein complex; The formation of covalent binding take longer than the seconds/few minutes which pass between drug exposure and start of anaphylaxis symptoms; For some drugs (e.g., sulfamethoxazole) the drug must first be metabolized into a reactive compound before it could bind (3, 18, 19); this would require hours, but symptoms occur within minutes (11). The gene discussed is IGHE; the disease is anaphylaxis.