I've heard some urban legends / 'drink party tales' about that particular liquor:
Jarzebiak was used as a medicine in the centuries past, particularly popular in XIX century, assigned positive properties in states of leg veins inflammation, hemorroids, improving heart activity and digestion.(source)
The drinking stories though involve drinking way more than "medical dosage" but still significantly less than "what could kill a seasoned Pole" - amounts like 250-500ml per person (say, one or two 0.5l flasks between two friends, that's really not all that much by Polish standards). Effects supposedly involved loss of consciousness, ER diagnosing critical blood pressure drop, with systolic pressure dropping below 60mmHg, applying pressure-rising drugs intravenously, and saving the patient from brink of death.
Still, considering the source of these stories (drinking stories), I'd like to find if they have actual medical basis, or are just some coincidences.