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 biliary colic as can be seen on Styrax's page.
Styrax is a Warm herb that tastes Pungent and Sweet. It targets the Spleen and the Heart.
Its main actions are: Opens the Orifices and clears the Mind. Stops pain
Coma Stroke Chest congestion Coronary artery disease Convulsions in children Seizures in children