Paula’s Choice C15 Super Booster Review: What’s New in the Formula?

Visit C15 Super Booster from Paula’s Choice is one of the brand’s best-selling vitamin C serums. It has just been rewritten. The promise: a gentler formula, less irritation, and better results thanks to new active ingredients. I compared the old and new ingredient lists, line by line, to see what really changes for your skin.

What remains the same: the core of the formula

The serum profile remains unchanged, which is good news. It includes:

15 % of pure vitamin C (L-ascorbic acid) Second on the list is the form of vitamin C with the most research supporting its effects on radiance, even skin tone, and the stimulation of collagen synthesis (Pullar JM et al., Nutrients, 2017).

Source : Pullar JM et al. The Roles of Vitamin C in Skin Health. Nutrients. 2017.

Ferulic acid, an antioxidant that stabilizes vitamin C and enhances protection against oxidative stress, as well as the vitamin E (tocopherol) : This combination of vitamins C, E, and ferulic acid is a long-established classic in antioxidant photoprotection (Lin FH et al., J Invest Dermatol, 2005).

Source : Lin FH et al. Ferulic acid stabilizes a solution of vitamins C and E. J Invest Dermatol. 2005.

What Really Changes: A Comparison Ingredient by Ingredient

Please note: the Phenoxyethanol remains present in the new formula (at the very end of the list, along with sodium phytate and citric acid). This is therefore not a change in preservatives but an adjustment to the active ingredients and texture.

1. The Introduction of Ergothioneine

This is the most interesting addition. The’ergothioneine is a powerful natural antioxidant capable of neutralizing free radicals and has been studied for its role in protecting cells (Halliwell B et al., FEBS Letters, 2018). Combined with vitamin C and ferulic acid, it strengthens the serum’s overall antioxidant shield, which supports the claim of ’enhanced effectiveness.«.

Source : Halliwell B et al. Ergothioneine, an adopted orphan. FEBS Letters. 2018.

2. Two new smoothing peptides

Visit Tridecapeptide-1 and the Palmitoyl Tripeptide-5 replace the previous peptide. These are signaling peptides known to improve skin firmness and smooth out fine lines, with a favorable safety profile. They provide a consistent «gentle anti-aging» boost, although their position in the list suggests that they are used in moderate concentrations.

3. The removal of propyl gallate and a revised preservation method

The old formula contained propyl gallate, a synthetic antioxidant sometimes identified as a contact allergen. It has been removed from the new version and functionally replaced by ergothioneine and a system of glycols (decylene glycol, 1,2-hexanediol, pentylene glycol), which contribute to both hydration and preservation. However, to be precise: the Phenoxyethanol remains present (last item on the list). The reformulation therefore does not involve a change in the primary preservative, but rather a removal of secondary ingredients and the addition of antioxidants.

4. The pH has risen slightly: 3.1 to 3.5

A key technical point. Pure vitamin C requires an acidic pH (below 3.5) to remain stable and penetrate effectively. The previous version had a pH of around 3.0. The new version has a pH of 3.1 to 3.5 : still within the effective range, but slightly less aggressive. It is precisely this type of adjustment that reduces the risk of tingling without sacrificing the active ingredient’s effectiveness—the most likely explanation for the phrase «minimized irritation.».

Tolerance Verdict (Dr. David's Rule)