Allergic Reaction?

Four year old got out of the bath and the tops of her hands were bright red. No soap was used, just water.

She says that they hurt but not to the touch. There is no other redness anywhere on her body.

Her palms are normal. It’s almost like a sunburn but it doesn’t behave like one.

No fever, nothing else is wrong.

Any ideas?

I gave her some Tylenol for the pain to help her sleep tonight but I’m wondering if I should also administer some Benadryl?