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 inflammation of the stomach as can be seen on Snake Gourd Root's page.
Snake Gourd Roots is a Cold herb that tastes Bitter, Sour and Sweet. It targets the Stomach and the Lung.
Its main actions are: Clears Heat in the Lungs and moistens Dryness, especially when there is Phlegm that is aggravating the condition. Brings down inflammation and reduces pus.
Dry cough Bloody sputum Inflammation of the lungs Sores Carbuncles