The 3rd-generation GnRH antagonists display a more tolerable side effect profile compared to the first-generation GnRH antagonists (histamine release and severe allergic reactions) and the second generation GnRH antagonists (allergy and gel formation); some of the GnRH antagonists approved for clinical use by the US FDA include cetrorelix (Cetrotide; Serono) and ganirelix (Antagon; Organon International). Here, GNRH1 is linked to Allergy.