first be sure that it is indeed hives (urticarial). it would be uncommon for hives just to occur in the genital area so see a medical provider so this skin eruption can be properly identified. if it is an allergic reaction some common causes would be soap or laundry detergents. otc hydrocortisone cream can be used safely in this sensitive area for an allergic response (hives is usually allergic) but if the cause is something other than allergy like a fungal skin eruption hydrocortisone cream could make things worse. this is why getting properly diagnosed first is the best step.
what cream is best for hives on children. on the genitals