Kiehl's Ultra Pure High-Potency 5.0% Niacinamide Serum Versus PCA Skin Hyaluronic Acid Boosting Serum

Kiehl's Ultra Pure High-Potency 5.0% Niacinamide Serum Versus PCA Skin Hyaluronic Acid Boosting Serum Detailed comparison of Kiehl's Ultra Pure High-Potency 5.0% Niacinamide Serum versus PCA Skin Hyaluronic Acid Boosting Serum. This oil-control serum is formulated around Niacinamide to balance excess oil and refine the look of pores. This hydrating serum is formulated around Niacinamide and Sodium Hyaluronate to hydrate skin and strengthen the skin barrier. Water Niacinamide Glycerin Propanediol Methyl Gluceth-20 Hydroxyacetophenone Sodium Hyaluronate Caprylyl Glycol Carbomer Sodium Hydroxide Water, Niacinamide, Glycerin, Propanediol, Methyl Gluceth-20, Hydroxyacetophenone, Sodium Hyaluronate, Caprylyl Glycol, Carbomer, Sodium Hydroxide Dimethicone Hydrolyzed Yeast Extract Polyglyceryl-3 Beeswax Coconut Alkanes Phenoxyethanol Isododecane Jojoba Esters Dimethicone Crosspolymer Polysilicone-11 Sodium Benzoate Xanthan Gum Hydrolyzed Hyaluronic Acid Cetyl Alcohol Polyglyceryl-6 Distearate Sodium Lauroyl Lactylate Disodium Acetyl Glucosamine Phosphate Hydrolyzed Glycosaminoglycans Ethylhexylglycerin Hexylene Glycol Polygonum Bistorta Root Extract Cetyl Hydroxyethylcellulose Rosmarinus Officinalis Leaf Oil Aroma Polyglucuronic Acid Ceramide NP Hyaluronic Acid Sodium Carrageenan Ceramide AP Phytosphingosine Cholesterol Lecithin Maris Sal Ceramide EOP Water, Propanediol, Glycerin, Niacinamide, Dimethicone, Hydrolyzed Yeast Extract, Polyglyceryl-3 Beeswax, Coconut Alkanes, Phenoxyethanol, Isododecane, Jojoba Esters, Dimethicone Crosspolymer, Polysilicone-11, Sodium Hyaluronate, Sodium Benzoate, Carbomer, Xanthan Gum, Hydrolyzed Hyaluronic Acid, Cetyl Alcohol, Polyglyceryl-6 Distearate, Sodium Lauroyl Lactylate, Disodium Acetyl Glucosamine Phosphate, Hydrolyzed Glycosaminoglycans, Ethylhexylglycerin, Sodium Hydroxide, Hexylene Glycol, Polygonum Bistorta Root Extract, Cetyl Hydroxyethylcellulose, Rosmarinus Officinalis Leaf Oil, Aroma, Polyglucuronic Acid, Ceramide NP, Hyaluronic Acid, Sodium Carrageenan, Ceramide AP, Phytosphingosine, Caprylyl Glycol, Cholesterol, Lecithin, Maris Sal, Ceramide EOP These ingredients are found in both products. Ingredients higher up in an ingredient list are typically present in a larger amount. Caprylyl Glycol is a humectant, skin conditioner, emollient, and preservative booster derived from either caprylic acid or synthetically created. Typical use levels vary from 0.3-1% as a preservative booster and go up to 2% to condition skin. Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on). Carbomer is a synthetic thickening and gelling agent. It's basically the ingredient that gives a lot of serums, gels, creams, and sunscreens their smooth, non-sticky texture. Although legally permitted at very high levels, carbomers are normally used at concentrations below 1%. It also needs to be neutralized to actually thicken, and because it is a large molecule, it doesn't really penetrate the skin barrier. Allergy-wise, the risk is very low. Clinical studies show carbomers have low potential for skin irritation/sensitization even at concentrations up to 100%. A 2024 UK study patch-tested 1,302 patients and found true allergy to the parent group of carbomer to be rare with no confirmed relevant reactions. Glycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum. Topically, glycerin does several things at once: Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3. Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin. This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products. Just know very high concentrations (>40%) can feel tacky in low humidity. Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine. Niacinamide is a multitasking form of vitamin B3 that strengthens the skin barrier, reduces pores and dark spots, regulates oil, and improves signs of aging. And the best part? It's gentle and well-tolerated by most skin types, including sensitive and reactive skin. You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this. In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it. If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare. When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark sp