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When did she have chickenpox?
Were the hives present when she had the skin lesions of chickenpox or developed only later?
What medications was she on?
Any similar episodes before?
When was she vaccinated?
Hives due to pox virus is not usually seen.
Chickenpox vaccine can cause hives ( due to its gelatin content).
Motrin can cause hives.
Continue giving Benadryl.
If hives remain persistent, consult a dermatologist.