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Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide scores 8.9/9.8 vs Peter Thomas Roth FIRMx Collagen Moisturizer at 8.5/9.8. Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide wins for active ingredients.
Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide edges ahead, winning 2 of 5 attributes.
Scores last verified: June 2026
31 unique
8 in common
16 unique
Where Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide really shines is active ingredient strength, scoring 7.7 compared to Peter Thomas Roth FIRMx Collagen Moisturizer's 5.9. Its formula features Niacinamide, Acetyl Dipeptide-1 Cetyl Ester, and Adenosine in high positions, signalling meaningful concentrations.
Hydration Efficacy is another area of separation. Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide scores 9.4 here versus 9.1 for Peter Thomas Roth FIRMx Collagen Moisturizer. That difference comes down to how each formula is built — the ingredient list tells the story.
Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide brings Niacinamide, Acetyl Dipeptide-1 Cetyl Ester, and Adenosine as actives, while peter Thomas Roth FIRMx Collagen Moisturizer relies on Collagen, Niacinamide, and Palmitoyl Tripeptide-1. Both approaches have merit, but the positioning and supporting ingredients make the difference.
Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide is better if you have
Peter Thomas Roth FIRMx Collagen Moisturizer is better if you have
Both sit in the premium bracket, so value comes down to formulation quality. Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide gets the nod here with its 8.9 overall score — you're getting more for a similar outlay.
Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide edges ahead with a slightly stronger formulation, but Peter Thomas Roth FIRMx Collagen Moisturizer is still a solid pick.
Based on ingredient analysis, Kiehl's Since 1851 Micro-Dose Anti-Aging Retinol Serum with Ceramides & Peptide scores higher overall. See the full score breakdown above for details on each attribute.
Yes, they share common ingredients. Check the ingredient face-off section above for a detailed comparison.
The key differences are in their active ingredients and formulation approach. Check the attribute battle above for a detailed breakdown.
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