Biologique Recherche Lotion P50 Versus SkinCeuticals Cell Cycle Catalyst Serum

Biologique Recherche Lotion P50 Versus SkinCeuticals Cell Cycle Catalyst Serum

This smoothing toner is formulated around Gluconolactone and Lactic Acid to refine skin texture and refine the look of pores.

This smoothing serum is formulated around Glycolic Acid and Lactic Acid to refine skin texture and brighten dull-looking skin.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Gluconolactone

Lactic Acid

Glycerin

Propylene Glycol

Niacinamide

Citric Acid

Ethoxydiglycol

Magnesium Chloride

Malic Acid

Vinegar

Phytic Acid

Salicylic Acid

Cochlearia Armoracia Root Extract

Arctium Lappa Root Extract

Rumex Acetosa Leaf Extract

Myrtus Communis Extract

Commiphora Myrrha Resin Extract

Allium Cepa Bulb Extract

Thymus Vulgaris Flower/Leaf Oil

Sulfur

Sorbitol

Phenoxyethanol

Sodium Benzoate

Potassium Sorbate

Water, Gluconolactone, Lactic Acid, Glycerin, Propylene Glycol, Niacinamide, Citric Acid, Ethoxydiglycol, Magnesium Chloride, Malic Acid, Vinegar, Phytic Acid, Salicylic Acid, Cochlearia Armoracia Root Extract, Arctium Lappa Root Extract, Rumex Acetosa Leaf Extract, Myrtus Communis Extract, Commiphora Myrrha Resin Extract, Allium Cepa Bulb Extract, Thymus Vulgaris Flower/Leaf Oil, Sulfur, Sorbitol, Phenoxyethanol, Sodium Benzoate, Potassium Sorbate

Glycolic Acid

Sodium Hydroxide

Mandelic Acid

Taurine

Chlorphenesin

Caprylyl Glycol

Tetrasodium Glutamate Diacetate

Water, Glycerin, Glycolic Acid, Ethoxydiglycol, Sodium Hydroxide, Phytic Acid, Lactic Acid, Mandelic Acid, Taurine, Salicylic Acid, Chlorphenesin, Caprylyl Glycol, Tetrasodium Glutamate Diacetate

Reviews

Alternatives

Ingredients Explained

These ingredients are found in both products.

Ingredients higher up in an ingredient list are typically present in a larger amount.

Ethoxydiglycol (aka Diethylene Glycol Monoethyl Ether) is one of the cosmetic world's quiet problem solvers.

In a formula, it is a solvent that dissolves tricky ingredients that don't want to mix in and helps spread ingredients evenly across your skin without leaving a greasy or sticky feeling

This makes it great for hard-to-dissolve actives like vitamin C, benzoyl peroxide, and self-tanner DHA.

It also has mild humectant and penetration enhancer abilities so it can help some actives absorb a little deeper.

The penetration boost is backed by lab research: studies using human skin samples found it improved how well an active dissolves into the upper layer of skin rather than tearing down your skin barrier. Reviews of its mechanism also describe it interacting gently with the lipids and water in your outermost layer of skin.

Just know this penetration-enhancing effect is not universal. It helps a lot in some formulas and did very little in others (so the benefit really depends on the specific product).

Safety-wise, the evidence is reassuring. The Cosmetic Ingredient Review Expert Panel reviewed it and concluded it's safe for use in cosmetics and recognized it as non-irritating, non-sensitizing, and non-comedogenic in skincare.

Typical leave-on skincare usage lands around 1-10%. The EU has sets caps of 2.6% in non-spray products, 10% in rinse-offs, 7% in oxidative hair dye, and 5% in non-oxidative hair dye.

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.

Lactic Acid is another well-loved alpha hydroxy acid (AHA). It is gentler than glycolic acid but still highly effective.

Its main role is to exfoliate the surface of the skin by loosening the “glue” that holds dead skin cells together. Shedding those old cells leads to smoother, softer, and more even-toned skin.

Because lactic acid molecules are larger than glycolic acid, they don’t penetrate as deeply. This means they’re less likely to sting or irritate, making it a great choice for beginners or those with sensitive skin.

Like glycolic acid, it can:

Lactic acid also acts as a humectant (like hyaluronic acid). It can draw water into the skin to improve hydration and also plays a role in the skin's natural moisturizing factor (NMF) in the form of sodium lactate.

Studies show it can boost ceramide production to strengthen the skin barrier and even help balance the skin’s microbiome.

To get results, choose products with a pH between 3-4.

Lower strengths (5-12%) focus on surface exfoliation; higher strengths (12% and up) can reach deeper in the dermis (deeper, supportive layer) to improve skin texture and firmness over time.

Though it was originally derived from milk, most modern lactic acid used in skincare is vegan. It is made through non-dairy fermentation to create a bio-identical and stable form suitable for all formulations.

When lactic acid shows up near the end of an ingredient list, it usually means the brand added just a tiny amount to adjust the product’s pH.

Legend has it that Cleopatra used to bathe in sour milk to help reduce wrinkles.

Lactic acid is truly a gentle multitasker: it exfoliates, hydrates, strengthens, and brightens. It's a great ingredient for giving your skin a smooth, glowing, and healthy look without the harshness of stronger acids.

Read more about some other popular AHA's here:

Phytic Acid is a gentle AHA and antioxidant. AHAs are chemical exfoliants that help remove dead skin cells. Phytic Acid has a slight and mild exfoliating effect.

The chemical makeup makes it classified as an AHA, much like lactic acid.

In some cases, it is a chelating agent. Chelating agents help prevent metals from binding to water, helping to stabilize the ingredients in a product.

An interesting fact about phytic acid is that it is considered an antinutrient. People do not have the enzyme needed to properly breakdown and digest phytic acid. When ingested, phytic acid binds to minerals and prevents them from being absorbed.

Salicylic Acid (also known as beta hydroxy acid or BHA) is a well-known ingredient for treating skin that struggles with acne and clogged pores. It exfoliates both the skin's surface and deep within the pores to help clear out buildup, control oil, and reduce inflammation.

Unlike AHAs (alpha hydroxy acids), salicylic acid is oil-soluble. This allows it to penetrate into pores which makes it especially effective for treating blackheads and preventing future breakouts.

Salicylic acid is also known for its soothing properties. It has a similar structure to aspirin and can calm inflamed or irritated skin, making it a good option for acne-prone skin that is also sensitive.

Concentrations of 0.5-2% are recognized by the U.S. FDA as an over-the-counter topical acne product.

It can cause irritation and/or dryness if one's skin already has a compromised moisture barrier, so it's best to focus on repairing that before introducing this ingredient into your routine.

While salicylic acid does not increase sun sensitivity, it’s still important to wear sunscreen daily to protect your skin.

If you are looking for the ingredient called BHA or Butylated Hydroxyanisole, click here.

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!

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