Although the popular beauty ethic of The Middle Ages was that of natural beauty - that didn't stop the ladies of the day from employing a bit of artifice to create the illusion of it...
Medieval skin care focused on achieving a smooth, clear visage with no spots or blemishes (displaying health and lack of smallpox). Preparations to even skin and removed freckles were common - cucumber and strawberry juice, rosemary infused wine or vinegar, as well as other potions containing powdered bulbs, roots, seeds and plant distillates. Other more bizarre treatments included ingredients such as donkey milk, horse manure, bull's blood and even distilled raven.
Could natural, flawlessly pale skin not be achieved, white, sometimes pink or flesh colored paint was commonly used by upper-class women, as well as ladies-of-the-night. Sometimes this paint was a pigment mixed with water and applied or was simply a white powder, the goal of which was to create the look of pale, smooth, flawless skin.
Similar to white face paint, rouge was also used through the Middle Ages by both affluent women and prostitutes, although more frequently by the former. Depending on the region and social standing, colors ranged from rose to orange to bright pink to earthy red. Full, red lips were also prized in the 14th Century.
Although not frequently depicted in art or always thought of as proper, eye shadow and eyeliner did exist in the Middle Ages. Shadows in shades of gray, green, brown and blue were used, as well as black liner on the upper lid. Liner was, similar to Egyptian eye kohl, a black pigment mixed with water or salive and applied with a stick.
Brows were worn natural until the 14th century when they were then plucked into a thin line, along with plucking their hairline to show a large expanse of forehead.
Pretty saucy stuff for a Medieval gal...;)
Source for information: Fashions in Makeup by Richard Corson 1972