According to HowStuffWorks, red blotches on the face can be caused by rosacea, eczema or reactions to skin care products, including allergic reactions. People who are photosensitive can also find themselves with red blotches on the face as a result of sun exposure.
As WebMD points out, rosacea is not contagious. It runs in families and most often occurs in those with northern European heritage. Rosacea is usually treated with oral antibiotics. Other lifestyle treatments include staying away from alcohol, spicy foods, stress and sun exposure, as well as using only hypoallergenic and noncomedogenic skin products and cosmetics.
Skin care products, cosmetics and laundry detergents can cause reactions that produce red blotches in the face in those who do not have a medical condition, as HowStuffWorks explains. One should change products used and then get allergy testing if the problem continues.