Though rare, it is possible to have a delayed allergic reaction to an insect sting, according to PubMed. A delayed allergic reaction produces symptoms as typical as anaphylaxis, or it may cause less typical symptoms such as those of serum sickness.
Other conditions that are potentially caused by a delayed allergic reaction include Guillain-Barr? syndrome, neuropathies, glomerulonephritis and myocarditis, according to Cleveland Clinic.
It is unknown what causes delayed allergic reaction to insect stings, explains PubMed. The cause is thought to be most likely an immunologically mediated, type III hypersensitivity reaction. The symptoms are mediated with venom-specific immunoglobulin E. It is recommended that patients experiencing a delayed allergic reaction are treated with venom immunotherapy.