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 syphilis as can be seen on Smilax Glabra Root's page.
Smilax Glabra Roots is a Neutral herb that tastes Sweet. It targets the Liver and the Stomach.
Its main actions are: Expels Damp-Heat especially from the skin. Clears Heat and dispels Dampness. Dispels toxicity such as Syphilis.
Urinary tract infection Dysuria Leukorrhea Carbuncles Lymphadenitis Eczema Lyme disease