6.7

Kiehl's Since 1851

Ultra Pure High-Potency 5.0% Niacinamide Serum

Name: Kiehl's Since 1851 Ultra Pure High-Potency 5.0% Niacinamide Serum
Brand: Kiehl's Since 1851

serumpremium

Overall score6.7

Kiehl's Since 1851 Ultra Pure High-Potency 5.0% Niacinamide Serum scores 6.7/9.8 overall. It ranks highest in low irritation risk (9.5) and formulation safety (9.0).

✶ Hero ingredients

#2Niacinamide

Vitamin B3 that brightens and strengthens skin barrier

#3Glycerin

One of the most effective humectants

#4Propanediol

Draws in moisture

Score breakdown

Overall

6.7

Hydration Efficacy4.5

Irritation Risk9.5

Active Ingredient Strength3.6

Ingredient Transparency7.5

Formulation Safety9.0

Estimated — based on ingredient analysis. Scores refine as user reviews are added.

Scores last verified: June 2026

What makes Kiehl's Since 1851 Ultra Pure High-Potency 5.0% Niacinamide Serum stand out

Kiehl's Since 1851 Ultra Pure High-Potency 5.0% Niacinamide Serum is a solid serum with an overall score of 6.7/9.8. Positioned in the premium bracket, it delivers a well-rounded formulation that balances efficacy with gentleness. The formula leads with Niacinamide, Glycerin, Propanediol — ingredients that actively target skin concerns.

It performs well on low irritation risk (9.5). On the flip side, hydration could be stronger and active ingredient concentration is on the lighter side.

Is this right for you?

Great for

✓Sensitive skin — low irritation risk with a gentle formulation
✓Safety-conscious shoppers — clean formulation with minimal flags
✓Ingredient-aware buyers — transparent, well-documented formula

May not suit

⚠Very dry skin types looking for heavy-duty moisture
⚠Those seeking potent actives — this leans more maintenance than treatment

Key ingredients

✶
Niacinamide
Works on your skin — #2 in the INCI list
✶

Full ingredient list

10 ingredients — listed in INCI order (highest concentration first)

#1Aqua/Water #2Niacinamide #3Glycerin #4Propanediol #5Methyl Gluceth-20 #6Hydroxyacetophenone #7Sodium Hyaluronate #8Caprylyl Glycol #9Carbomer

Compare with similar products

Ingredient breakdown

Some links on this site are affiliate links. We may earn a commission from purchases made through our links, at no extra cost to you. This helps us keep Gracie free and independent.

Glycerin

Draws in moisture — #3 in the INCI list

✶

Propanediol

Draws in moisture — #4 in the INCI list

✶

Methyl Gluceth-20

Draws in moisture — #5 in the INCI list

✶

Sodium Hyaluronate

Draws in moisture — #7 in the INCI list

#10

Sodium Hydroxide

Draws in moisture4
Keeps the product fresh2
Other ingredient1
Works on your skin1
Holds the formula together1
Formula balancers1