Hi,
Redness, swelling, or irritation within one inch of the site of the injection is normal. These symptoms should
go away within 4 to 8 hours after receiving the shot. They should not appear again. I think you need to
consult your doctor for the same as a reappearance of the redness/swelling is not normal. However, I must tell
you that since you have not developed any other symptoms to the allergy shot like difficulty in breathing
which are more sinister, I don’t think there should be anything serious to worry about.
Many cases of hives are idiopathic (for which the cause is not known), however in your case they could be due
to the allergy shot. Hives can occur due to any allergy, viral infection or due to medications.
I hope that helps. Please do keep me posted in case of any additional clarification.
Best Regards.