Treatment for pimples was definitely something that was around long before the 19th century. There are surviving recipes going back to the Egyptians and from many times and regions in between. In Toilet of Flora, from the 18th century, there are a couple of recipes specifically for dealing with pimples (their term as well), as well as many others for better complexion, and even separate ones for dealing with things like small-pox pits.

"An excellent Water to clear the Skin, and take away Pimples.

Take two quarts of Water, in which a quantity of Horse-beans has been boiled till quite soft; put it into an alembic, and add two handfuls of Pimpernel, the same quantity of White Tansy, a pound of Veal minced small, six new laid Eggs, and a pint of White-wine Vinegar; distill this mixture in a water bath, and it will afford an excellent Lotion to remove all eruptions on the face, if washed with it every night and morning."

"A Water for Pimples in the Face.

Boil together a handful of the herbs Patience, and Pimpernel in Water; and wash yourself every day with the decoction."

Throughout the 19th century and other parts of history Sulphur was used and still is successful today. And, of course, the simple act of washing the face was nearly always considered a basic necessity for keeping clearer skin. Other elixirs came about in the late 19th century, some more valid than others. Many were still based in the use of things like sulphur, vinegar, or other stringent products that help to clean off oils. The Ladies Stratagem calls to "Squeeze out the juice of a leek, mix it with an equal quantity of sweet milk or cream, and use it to wash the pimples, which will dry up and promptly go down without leaving spots."