It originally included the ingredient naphtha, effective for cleaning laundry and removing urushiol (an oil contained in poison ivy).

Joseph's younger brother Samuel Simeon Fels was the new company's first president and held that position until he died in 1950.

It is intended for the pre-treatment of stains by rubbing the dampened product on a soiled area prior to laundering.

According to the manufacturer, about 1/2 of a bar of Fels-Naptha grated and added to a wash cycle helps eliminate residual stains.

[9] In its 2007 material safety data sheet,[10] Dial Corp. states that Fels-Naptha can irritate the eyes and, with prolonged exposure, the skin.