Oshima Tsubaki Camellia Premium Shampoo

Being created from coconut oil means Cocamidopropyl Betaine is hydrating for the skin.

While Cocamidopropyl Betaine was believed to be an allergen, a study from 2012 disproved this. It found two compounds in unpure Cocamidopropyl Betaine to be the irritants: aminoamide and 3-dimethylaminopropylamine. High-grade and pure Cocamidopropyl Betaine did not induce allergic reactions during this study.

That profile makes it a classic emollient; it works by hanging out with the skin's surface lipids, softens, and slows down water loss.

The most cited study on it was done on skin cells in a dish where this oil got them to make more of the building blocks for collagen while also slowing down the enzyme that breaks collagen down. Researchers tested this on human skin too; it didn't cause irritation and helped skin hold onto moisture better.

Another study done on cells and mice found this oil quieted down some of the body's inflammation signals.

These studies are still small, early, and not done on humans, so it's best to think of this ingredient as a great supporting ingredient for the rest of your routine and not the main active.

Concentrations can range from 1-5% in serums to 100% as a single face oil (how it's most traditionally used).

Because this ingredient is a triglyceride of long-chain fatty acids, this ingredient may not be Malassezia safe.

Allergies to this protein are quite rare as the refined seed oil contains very little residual protein. Human irritation testing also came back clean. But it is a plant and as with any botanical ingredient, contact allergy is possible.

A separate study found the flower extract had solid antioxidant activity and reduced the reactive oxygen species that urban air pollution triggers in skin cells.

Newer work also points at anti-aging and calming effects:

One 2025 paper tied the extract and its component hyperoside to collagen III and elastin production plus better skin-barrier protein expression. A mouse study on eczema-like skin found four weeks of topical camellia extract reduced inflammation and itch-related markers.

Just know that most of these studies are cell-culture and animal work and not human trials. For now, it's best to treat it as a nice supporting antioxidant rather than a headline active.

At this time, there's no published regulatory use-level for this specific ingredient; suppliers usually sell it as a water/glycerin-based extract used in the low single-digit percent range.

There's no published contact-allergy case reports for this ingredient but as with any botanical, a patch test is sensible if you react to plant extracts generally.

This extract is created by using 50% 1,3-Butylene glycol.

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.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

For haircare friends: this ingredient is not a silicone.

Due to the large molecule size, this ingredient is unlikely to penetrate skin.

However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.

Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.

In skincare formulas, citric acid can:

While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.

Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.

Read more about some other popular AHA's here:

You might see people debate whether Sodium Chloride is comedogenic, but there actually haven't been any comedogenic tests done on it. Either way, the overall formulation of a product matters a lot more than any single ingredient.

You might see this ingredient used in scrubs as a primary exfoliating ingredient.

This is also one of the most heavily studied preservatives out there and major regulatory bodies have repeatedly given it the green light.

In 2023, the EU's Scientific Committee on Consumer Safety (SCCS) confirmed that this ingredient is safe up to 0.4% on its own, of up to 0.8% when mixed with other paraben esters.

Here's the science behind the noise behind parabens/hormones as well:

Methylparaben shows very weak estrogen-like activity in vitro tests (more than 1,000x weaker than your body's own estradiol). In vivo (live-organism) studies don't support a meaningful endocrine-disrupting effect either.

You get a stronger estrogenic effect from eating tofu, actually.

It's also a low sensitizer and allergic reactions are uncommon; they usually happen on damage or broken skin.

There is a caveat: France has proposed to formally re-examine its endocrine classification in 2025 so the regulatory conversation isn't fully closed as of yet.

But as it stands today, this ingredient is considered safe at permitted levels.

You'll likely see it paired with methylparaben to cover the full range (including gram-negative bacteria).

This ingredient is effective at low concentrations (~0.2-0.5%) and stable across a wide pH range (4.5-7.5 pH). It's effectiveness drops off above pH 8 and it can lose potency when combined with non-ionic surfactants like polysorbate 80 due to micellization.

The regulatory bodies have concluded this ingredient to be safe as used in cosmetics. The EU has capped it at 0.14% and combined parabens are not to exceed 0.8%.

While parabens do cross the stratum corneum, only about 1% remains for absorption into the body. This is because most of it is metabolized within living skin.