Rich in the polyphenol EGCG, a strong antioxidant in the lab. Small studies hint at help for acne; anti-aging results in people have been disappointing.
Green tea's catechins, especially EGCG, neutralize oxidants, calm inflammation and reduce sebum and acne-bacteria activity in lab studies. Extracts go into cleansers, toners, sunscreens and moisturizers, often at low, unstated levels, and catechins oxidize easily.
A concentrated green-tea catechin ointment exists as a prescription drug for genital warts; that is a far higher dose and a different product from cosmetic extracts.
An 8-week trial of 10% green tea cream plus oral green tea found no visible improvement in photoaging over placebo, only changes on biopsy. A small uncontrolled study of 2% green tea lotion found fewer acne lesions after 6 weeks. Lab evidence is strong; clinical evidence at cosmetic doses is limited.
40 women with moderate photoaging used 10% green tea cream plus 300 mg oral green tea twice daily, or placebo, for 8 weeks; no clinical difference was seen, only improved elastic tissue on biopsy, and the green tea group reported more irritation.
20 patients with mild-to-moderate acne applied 2% green tea lotion twice daily for 6 weeks; the average lesion count fell from 24 to 10. There was no control group.