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 hepatosplenomegaly as can be seen on Red Sage Root's page.
Its main actions are: Invigorates the Blood, breaks up Stasis and eases pain. Clears Heat and calms restlessness.