I never had hives (knock on wood, and praise the lord), but my son had a severe case of "giant hives" when he was about 8 months old. Babies do not have the concept of stoicism or suffering in silence, so I know it's uncomfortable. The only thing that gave him any relief was holding him in my arms in the neighbor's swimming pool with him submerged up to his neck.
Not really off topic PG. Its about Effinex having hives. Good info here