3. Milk of Magnesia – If you struggle with extremely oily skin and nothing else seems to beat the shine, try Milk of Magnesia! This laxative liquid doubles as an extreme mattifier, and can either be mixed in with moisturizer, or applied with a cotton round all over the face right before makeup application. Tip: A few drops will go a long way with this product. If you use too much at once, the liquid can leave a dry, whitish residue on the skin. Also, be sure to use the original formula – veer away from any flavored or scented variations.