Entire back of upper arm to swollen after allergy shot

June 15, 2004

This does occur sometimes, even when the proper dose is administered. Allergy shots provide increasing amounts of the items you are allergic to (allergens). As the dose is gradually increased, your body gradually builds immunity to the allergens received through the injection. When local swelling occurs that is 30 mm or greater in size (approximately the size of a fifty cent piece in U.S. currency), your body is saying, "Whoa...it's time to slow down a bit and let me catch up!"

You should definitely tell the nurse providing your injections about any local reactions before receiving your next injection. If you have a large local reaction, such as you describe above, you should phone the office to let them know when it occurs.

We instruct our patients to apply cold packs when a local reaction occurs. We also tell our patients to be sure they take their antihistamine the day they receive their allergy shot if they are experiencing increased symptoms such as runny nose or swelling. If they experience wheezing, or swelling larger than 30 mm, we cut back on the dose. In some situations, we cut back on the dose if the patient experiences smaller local reactions, or any increase in symptoms.

See also my item:
How do allergy shots work? How many? How often?

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