What is the onset of symptoms of anaphylaxis following exposure to trigger?

Updated: May 16, 2018
  • Author: S Shahzad Mustafa, MD; Chief Editor: Michael A Kaliner, MD  more...
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Symptoms usually begin within 5-30 minutes from the time the culprit antigen is injected but can occur within seconds. If the antigen is ingested, symptoms usually occur within minutes to 2 hours. In rare cases, symptoms can be delayed in onset for several hours. Parenteral administration of monoclonal antibodies and oral ingestion of mammalian meat (eg, beef, pork, lamb) have recently been reported to be potential causes for anaphylaxis characterized by delayed onset. [52, 53, 54, 55, 56] It must be remembered that anaphylaxis can begin with relatively minor cutaneous symptoms and rapidly progress to life-threatening respiratory or cardiovascular manifestations. In general, the more rapidly anaphylaxis develops after exposure to an offending stimulus, the more likely the reaction is to be severe.

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