Inert earth mineral used as a thickening, whitening, lubricating, and sunscreen ingredient in cosmetics. Along with titanium dioxide, zinc oxide is considered to have no risk of skin irritation. It can also be an anti-irritant and potentially an antioxidant.

(Sources: Journal of Postgraduate Medicine, July 2004, pages 131–139; International Journal of Dermatology, July 2003, page 505; Wound Repair and Regeneration, May 2002, page 130; Alternative Therapies in Health and Medicine, May–June 2001, pages 49–56; and Scandinavian Journal of Plastic and Reconstructive Surgery, December 1994, pages 255–259.)

Anecdotally, pure zinc oxide (like those found in diaper rash creams) are great as a spot treatment for inflamed acne pimples due to its anti-irritant and astringent properties. However, it’s not as drying and skin-wrecking as alternative spot treatments like benzoyl peroxide.

In formulas it’s insoluble but dispersible in water and oils. It’s maximum usage level in formulas in the USA is 25% and there is no limit in Japan.