Biphasic anaphylactic reaction

It is usual to give a sedating antihistamine, for example chlorphenamine 10 mg by intramuscular or slow intravenous injection, because of the relatively short half-life of epinephrine (adrenaline), and because of the active role of histamine in anaphylaxis. In addition, the inflammatory reaction can be moderated by the administration of a corticosteroid, such as hydrocortisone 200 mg by intramuscular or slow intravenous injection. Corticosteroids may take several hours to act, but can be of some help in so-called biphasic anaphylactic reactions. 

Anaphylactic reactions may exhibit a biphasic pattern. Different studies indicated a wide variation regarding the incidence of biphasic reactions. These range from 3 to 20% regarding the incidence of biphasic reactions. The time from the initial symptoms to the onset of the secondary reaction varied from >1 up to 47 h [36]. 

A Bone marrow depression, stomatitis, erythema. Anaphylactic reactions. IV. Long biphasic half-life. Hypotension w/rapid infusion. Testicular and lung cancers ... 

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