Tatcha Luminous Dewy Skin Night Concentrate

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

This is due to how structurally similar it is to what your skin already produces.

Though it is mostly an emollient that helps soften and hydrate skin, it also has some humectant and occlusive action. Humectants help the skin retain moisture while occlusives seal it in, making squalane a triple-threat moisturizer.

Research shows it has antioxidant capabilities that help protect against stressors like UV exposure, specifically UVA induced oxidative stress. This study also found that it supports collagen biosynthesis in human dermal fibroblasts.

No clinical study has reported significant adverse effects and irritation reactions are very rare from this ingredient (even at 100% concentration).

Overall, it's a fantastic ingredient for hydration and is suitable for all skin types.

This depends on the source. Squalane can be derived from both plants and animals. Most squalane used in skincare comes from plants.

Please note: the source of squalane is only known if disclosed by the brand. We recommend reaching out to the brand if you have any questions about their squalane.

Read more about squalene with an "e".

Though squalane is often called an oil, it’s technically not one. It is a hydrocarbon, meaning it is only made of carbon and hydrogen. True oils are triglycerides and made of fatty acids and glycerol.

The term “oil-free” isn’t regulated so companies can define it however they want. Some exclude all oils, while others just avoid mineral oil or comedogenic oils.

Squalane has a comedogenic rating of 1 from the original 1972 study that tested raw ingredients under occlusion on rabbit ears. This system is not standardized or peer-reviewed, and using the raw ingredients is very different from how diluted cosmetic formulations are used on human skin.

A comedogenic rating of 1 means it is "unlikely to clog pores" according to the original rating system.

The overall formula of a product matters more than the individual ingredients on whether or not it will cause clogged pores.

The safety profile of this ingredient is reassuring; the US CIR Expert Panel concluded D5 is safe as used in cosmetics and Health Canada concluded that D5 is not harmful to human health or the environment as currently used in cosmetics

There's a study that people mention about D5 in a rat study showing tumors. This study is related to long-term inhalation of high D5 levels.

Regulatory bodies have judged this study to be not applicable in topical skincare since skin absorption of D5 is very low and we're not really inhaling huge amounts of D5.

The only restriction for this ingredient is environmental. The European Chemicals Agency (ECHA) restricted D5 in wash-off cosmetics at or above 0.1% due to their persistence in water.

It is also an emollient and helps condition the skin.

One of the standout features of ginseng is its ability to improve blood circulation and oxygen delivery to the skin, bringing a fresh supply of nutrients to support overall skin health. It also has antioxidant and anti-inflammatory properties. This helps to protect your skin against damage from UV exposure, pollution, and daily stress.

Additionally, studies suggest that ginseng may help reduce hyperpigmentation by inhibiting tyrosinase, the enzyme involved in melanin production.

There are different types of ginseng used in skincare, and while they all share core benefits, their potency can vary.

Most products use fresh or white ginseng because it’s more affordable. However, red ginseng, produced by steaming the root, contains higher levels of ginsenosides, which are compounds with proven anti-aging effects. These ginsenosides help reduce the appearance of wrinkles and improve skin elasticity.

Note: All forms of ginseng are listed simply as “Panax ginseng” in ingredient lists. We recommend reaching out to the brand if you have questions about which type of ginseng is used in their ingredients.

For general antioxidant benefits, any ginseng extract will do, but for wrinkle care or firmer skin, red or fermented ginseng is often more effective.

In short, ginseng is a powerhouse ingredient that supports hydration, radiance, and resilience.

Studies show Royal Jelly to contain amino acids, fatty acids, and a variety of vitamins, including Vitamin Bs. Many of these components are antioxidants, which help with anti-aging. The fatty acids in Royal Jelly make it a hydrating ingredient.

Several animal studies show Royal Jelly to boost collagen production and reduce inflammation.

The Vitamin Bs found in Royal Jelly include:

Royal Jelly is derived from honeybees. This means it is not vegan.

Studies show green tea extract and its catechins (like epigallocatechin gallate (EGCG)) help your skin cells product energy more efficiently and reducing the number of free-radicals that can damage your skin from the inside.

In lab-grown skin models, this translated to younger, healthier, and stronger skin.

There's also good sun protection data; researchers saw less DNA damage and redness on human skin when green tea was applied before UVB exposure. And the more they applied, the better the protection.

Needless to say, this ingredient shouldn't replace your sunscreen. But it is a great supportive ingredient that you can already find in many sunscreens and antioxidant serums.

A 2009 study found a 2% green tea lotion was effective for mild-to-moderate acne thanks to its anti-inflammatory and mild antimicrobial activity.

The quality of the extract matters a lot here:

Good extracts contain 50-90% catechins while lower quality ones are mostly there for marketing. We recommend reaching out to the brand if you have questions about the quality or source of their ingredients.

Human Repeated Insult Patch Testing showed no irritation or sensitization at use concentrations (0.86% in leave-on products and up to 30% as leaf water).

Algae is rich in antioxidants. Antioxidants help fight free-radicals. Free-radicals are molecules that may damage your skin cells, such as pollution.

Algae can also help with soothing and hydrating skin.

Many different types of algae have different benefits.

In Chinese traditional folk medicine, Scutellaria Baicalensis Root Extract is used to help treat lung issues and hypertension.

Like other plant oils, this can help nourish the skin. The germ of rice is rich in oils, vitamins, minerals, antioxidants, and protein.

This ingredient may not be fungal-acne safe.

Learn more about the benefits of rice extract.

Keratinocytes make up the majority of the outermost layer of skin. These cells protect our skin from UV exposure, infection, and help keep skin hydrated.

This ingredient is also considered a humectant. Humectants help hydrate the skin by drawing moisture to it.

Emollients help your skin stay smooth and soft. It does so by creating a film on top of the skin that helps trap moisture in.

One in-vitro study found this ingredient to be effective at penetrating the skin barrier. Note the study focused on medicine delivery to the skin.

A perk of this ingredient is that it leaves skin feeling soft and silky after rinsing. This is why you'll even see it in baby washes.

Another perk?
The lauric acid backbone gives it mild antimicrobial activity and lauric acid itself has been shown to suppress acne-causing bacteria in lab studies.

In 2023, scientists took a close look at how SLL behaves and found it can break apart the fatty outer layers of cells. This is basically why it cleans well and can fight off certain microbes.

The Cosmetic Ingredient Review (CIR) Expert Panel has reviewed it and concluded it's safe as used.

A 2017 survey showed concentrations up to 10% are used in rinse-off cleansers and roughly 0.5-5% being typical in skincare.

Animal and reconstructed-skin testing found it to be non-irritating at 10%, and it's well tolerated even on sensitive skin. The only caveat is to patch test if you have a lactic acid allergy.

As a lactylate salt used at low co-emulsifier concentrations, this ingredient is less likely to break down and release free lauric acid on skin. This ingredient is fungal acne safe.

The Cosmetic Ingredient Review has found 4% of this ingredient in repeat-insult patch tests on humans to be non-sensitizing. There is a caveat that some reactions have shown up in patients with damaged or diseased skin.

Because it is an ester of a C18 fatty acid, it falls into the C11-24 range that the Malassezia yeast can metabolize. This means this ingredient may not be fungal acne safe.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.

Another name for this ingredient is polyoxyethylene decyltetradecyl ether/hexamethylene diisocyanate/polyethylene glycol 11000 copolymer.

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.

Emollients help keep your skin soft and hydrated by creating a film that traps moisture in.

In 2000, Behenyl Alcohol was approved by the US as medicine to reduce the duration of cold sores.

For instance, Habanolide is a proprietary trade name for a specific aroma chemical. When used as a fragrance ingredient in cosmetics, most aroma chemicals fall under the broad labeling category of “FRAGRANCE” or “PARFUM” according to EU and US regulations.

The term 'parfum' or 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term.

For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance by INCI standards.

One example is Calendula flower extract. Calendula is an essential oil that still imparts a scent or 'fragrance'.

Depending on the blend, the ingredients in the mixture can cause allergies and sensitivities on the skin. Some ingredients that are known EU allergens include linalool and citronellol.

Parfum can also be used to mask or cover an unpleasant scent.

The bottom line is: not all fragrances/parfum/ingredients are created equally. If you are worried about fragrances, we recommend taking a closer look at an ingredient. And of course, we always recommend speaking with a professional.

Is it bad for your skin?

The answer comes down to concentration. Patch and wash studies have found highly concentrated alcohol-based hand rubs (60-100%) cause less barrier disruption than washing with a basic detergent like SLS. The only measurable effect in these studies was a temporary dip in skin hydration.

Concentrations below 12-15% in leave-on cosmetics is generally well-tolerated. Concentrations above start to see increased transepidermal water loss (TEWL) and reduced hydration.

In concentrations about 58%, it creates temporary channels in your skin's lipid layers to become more permeable and allow other ingredients to slip through easily.

This ingredient can be up to 80% of the formula in alcohol-based perfumes.

Overall, this ingredient is probably harmless if found lower down an ingredients list but worth side-eyeing if it's high up (especially if your barrier is already struggling).

Alcohol can worsen dry skin, eczema, and oily skin, especially at higher concentrations. This is because it can increase transepidermal water loss and decrease hydration to disrupt the skin barrier.

According to the National Rosacea Society based in the US, you should be mindful of products with these alcohols in the top half of ingredients.

True allergic contact dermatitis to ethanol is uncommon, but be sure to patch test if you have dry or sensitive skin.

On a cellular level, it disrupts the cell membranes of microbes by poking holes that make the cell leak. This shuts down the chemical reactions the microbe needs to make energy so it can no longer survive.

Another perk of this ingredient is that it stays functional across a wide pH range (3-10).

You'll often see it paired with boosters like Ethylhexylglycerin; one study showed that a 1:9 ratio of Ethylhexylglycerin to Phenoxyethanol damages bacterial membranes as effectively as doubling the Phenoxyethanol concentration on its own.

Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.

Safety-wise, the fear mongering does not hold up to the evidence. The EU's Scientific Committee on Consumer Safety and FDA consider it safe as a preservative at up to 1%, including for children of all ages.

Adverse systemic effects only showed up in animal studies at exposures roughly 200x higher than what people get from cosmetics. And despite its very widespread use, this ingredient is a rare sensitizer and allergic reactions are uncommon.