Wife has got bad skin allergy since yesterday. large red spots (as huge mosquito bites). avil inj helped last night. why so? possible causes?

Hives: Cause food allergy- seafood, chocolate, peanuts, strawberries. Other causes medications either prescription or o/c. Could also be reqction to infection. Suppress with antihistamines and look for cause. If extensive and persistent see dermatologist or allergist for workup.

Urticia or Hives: The 2 most common causes are medications ( over the counter or prescription) and recent infections especially viral. Antihistamines will provide temporary relief of the symptoms. If the lesions persist a medical work up is needed.