Phenolax wafers contained a gentle laxative called phenolphthalein. They were introduced by The Upjohn Company in 1908, inside an embossed glass bottle with no label. Phenolax was an instant hit. Twenty million of these wafers were sold in the first year. In the 1930's, CEO Donald Gilmore made the comment that the house he had built on the Short Road in Kalamazoo was "the house that Phenolax built".

The product was sold by Upjohn until 1988, which is a staggering 80 years! This page contains a January 1986 article about it and photos of Phenolax wafers, bottles and a box. Here's a page that shows Phenolax store displays from the first half of the 20th Century.