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 hypersexuality as can be seen on Anemarrhena Rhizome's page.
Its main actions are: Clears Heat and Fire from the Qi level. Clears Heat and Fire from the Lung and Stomach. Clears Heat and tonifies the Yin.