Food Allergies/anaphylaxis


what is the time frame for severe allergic reactions such as anaphylaxis to occur. I have read different answers to this on the internet. Some say within mins, while some say it can sometimes take up to a few hours or more. These are very varied times given. Thank you for any info.

Sorry about the delay in answering - password problems.

The time taken for anaphylaxis to occur depends on the type of exposure i.e. Whether injected intravenously, intramuscular or subcutaneous. With i.v. it's a matter of a few seconds to 1-2 minutes. Rather longer with intramuscular and longer still with s.c. But even with that, one would expect it to have started within 15 minutes.

With most foods, anaphylactic reactions can start with itching in the mouth within 1-2 minutes. Milk is an exception, because some of it's allergens can still be present in partial digestion products.

There are also rare cases of food-dependant exercise-induced reactions. Reactions come on if exercise follows a relevant meal anything up to 3 hours later.

If there are no positive skin prick tests to the suspected allergen, then the chances of anaphylaxis are effectively zero. Hope this helps. Get back if it does not.

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David Pearson








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