Kiehl's Brightening Balance Brightening Spot Serum, also known as Anbai Bottle, has sold more than 600,000 bottles and is one of the products with the highest repurchase rate under the brand.
 
Among the whitening ingredients contained in the lightening serum, 3-o-ethyl ascorbic acid plays a leading role, which is a derivative of vitamin C. Vitamin C is an extremely commonly used whitening ingredient, but it is not easy to store and easily inactivated. 3-O-ethyl ascorbic acid also has a high inhibition rate of tyrosinase activity, which can reduce the production of melanin. In addition, 3-o-ethyl ascorbic acid is more stable than vitamin C, less prone to oxidation, and has lipophilic and hydrophilic properties, which is more suitable for adding to skin care products. Salicylic acid, another regular whitening ingredient, is also added, which accelerates the exfoliation of aging keratinocytes and reduces pigmentation. Salicylic acid and alcohol together control oil and inhibit bacteria, so the bottle is quite suitable for acne oily skin, but the essence has a strong irritation, sensitive skin should be used with caution.
 
The texture of the bottle is transparent and watery, and it spreads well and is easy to peel and apply. The skin feel is also relatively refreshing, even if it is used in summer, it is not sticky, and it is not easy to rub mud when layered with other products. The whitening essence is designed with a glass bottle and a dropper, which is easy to absorb and control the dosage, but the bottom essence cannot be adsorbed and still needs to be tilted to pour out.
 
Kiehl's Vitamin C Firming Serum Lotion, another popular serum, is directly infused with vitamin C at a concentration of up to 12.5%, while using dark packaging and oil-based solvents to maintain vitamin C activity. Due to the high concentration of vitamin C and propylene glycol, the skin tightening serum is highly irritating, and many users will experience a slight tingling sensation when using it for the first time, so it is recommended to stop using it if the skin feels uncomfortable.
 
In addition to the whitening serums, Kiehl's has also launched a Moisturizing Hydrogel Serum and a Night Repair Serum, the former focusing on moisturizing and brightening for basic skincare, while the latter emphasizes soothing and repairing benefits and is more friendly to sensitive skin. Men's Rejuvenation Serum Lotion is aimed at male users, moisturizing and moisturizing, while the essence texture is light and refreshing, and the skin feels good.