The information provided here is not a replacement for a doctor. You shouldn't use it for the purpose of self-diagnosing or self-medicating but rather so you can have a more informed discussion with a professional TCM practitioner.
Because it is a herb specifically indicated to treat hives as can be seen on Saposhnikovia Root's page.
Its main actions are: Relieves the Exterior and disperses Cold. Relieves Wind-Damp-Cold painful obstruction. Disperses Wind.
Because it is a herb specifically indicated to treat hives as can be seen on Stinging Nettle Leaf's page.
Stinging Nettle Leaves is a Cold herb that tastes Bitter and Pungent. It targets the Liver.
Its main actions are: Clears the meridians and expel wind-dampness. Smooth digestion and kills parasites.