Rationale #5 The Serum

Rationale #5 The Serum

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Overview

What it is

Serum with 55 ingredients that contains AHA, BHA and exfoliants

Cool Features

It is reef safe

Suited For

It has ingredients that are good for fighting acne, anti aging, dry skin, brightening skin, oily skin, reducing pores, scar healing, dark spots and better texture

Free From

It doesn't contain any harsh alcohols, parabens, silicones or sulfates

Fun facts

Rationale is from Australia. This product is used in 1 routines created by our community.

We independently verify ingredients and our claims are backed by peer-reviewed research. Does this product need an update? Let us know.

About this product

Ingredients List

Dive into the full list of ingredients.

26
14
15

Water

Skin Conditioning

Ethoxydiglycol

Humectant
0 / 0

Vaccinium Myrtillus Fruit Extract

Skin Conditioning

Dimethyl Isosorbide

Solvent

Salicylic Acid

Masking
BHA IconPreservative IconGood for Oily Skin IconGood for Minimizing Pores IconHelps fight Acne IconHelps brighten skin IconCan worsen Dry Skin IconMay worsen Eczema IconMay worsen Rosacea Icon

Key Ingredients

Benefits

Concerns

Ingredients Explained

Skin Conditioning, Solvent

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. Stay hydrated!

Learn more about Water
Humectant, Solvent

Ethoxydiglycol is a synthetic solvent.

Solvents are used to keep ingredients together in a product. They can help dissolve ingredients to stable bases or help evenly distribute ingredients throughout the product.

Ethoxydiglycol also helps deliver other key ingredients into the skin.

Learn more about Ethoxydiglycol

Vaccinium Myrtillus Fruit Extract comes from the bilberry plant. This plant is native to Eurasia.

Bilberry contains antioxidant compounds called anthocyanins. Anthocyanins help fight free-radicals. Free-radicals are molecules that may damage your skin cells. Fighting off these molecules can help reduce signs of aging.

Vaccinium Myrtillus Fruit Extract also helps reduce irritation.

Learn more about Vaccinium Myrtillus Fruit Extract

Dimethyl Isosorbide is a solvent and helps deliver actives into your skin. It is created from sorbitol.

As a solvent, dimethyl isosorbide helps dissolve other ingredients. This helps ensure even distribution of an ingredient. It may also be used to decrease the thickness of a product.

Studies show dimethyl isosorbide is able to penetrate skin to deliver other ingredients into the skin, making them more effective.

Learn more about Dimethyl Isosorbide
Masking, Preservative, Skin Conditioning

Salicylic Acid (also known as beta hydroxy acid or BHA) is one of the most well-known ingredients for treating skin that struggles with blackheads and acne. It helps to exfoliate both the skin's surface and pores, and also acts as an anti-inflammatory agent.

This multitasking property makes it a great ingredient for cleaning out pores, controlling oil production, and reducing inflammation.

Unlike AHAs which are water soluble, Salicylic Acid is oil soluble. This means that it's able to exfoliate the inside of pores and reduce blackheads.

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 a Salicylic Acid into your routine.

In general, Salicylic Acid is a great ingredient for oily acne-prone skin.

While salicylic acid does not increase sun-sensitivity, we still recommend wearing SPF.

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

Learn more about Salicylic Acid
Buffering, Humectant, Skin Conditioning

Lactic Acid is an AHA that is derived from fermenting lactose, a carbohydrate from milk. It removes the top layer of old and dead skin cells and helps increase cell turnover.

Benefits of Lactic Acid are that it can help to reduce large pores and reduce the effects of aging. Some potential downsides are that it can be bad for dry skin, cause irritation, worsen eczema, and worsen rosacea.

Not only does it help exfoliate the skin, it helps strengthen the skin's barrier. When applied, lactic acid helps the skin create ceramides.

Lactic acid is an over-the-counter chemical exfoliant that comes from the fermentation of lactose — a carbohydrate found in milk.

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

Read more about some other popular AHA's here:

Learn more about Lactic Acid
Moisturising, Skin Conditioning

This ingredient is also called sugarcane extract. It is a moisturizing humectant and has skin soothing properties.

Similar to hyaluronic acid, sugarcane can attract moisture to your skin.

Glycolic acid is a derivative of sugarcane. While glycolic acid is an AHA with exfoliating properties, sugarcane is not an AHA.

A study from 2021 found the compounds in sugarcane extract to have antioxidant, antimicrobial, and anti-inflammatory activity. The study also suggests these compounds can inhibit skin ageing enzymes and promote collagen synthesis.

Learn more about Saccharum Officinarum Extract
Humectant, Skin Conditioning, Skin Protecting

Glycerin is already naturally found in your skin. It helps moisturize and protect your skin.

A study from 2016 found glycerin to be more effective as a humectant than AHAs and hyaluronic acid.

As a humectant, it helps the skin stay hydrated by pulling moisture to your skin. The low molecular weight of glycerin allows it to pull moisture into the deeper layers of your skin.

Hydrated skin improves your skin barrier; Your skin barrier helps protect against irritants and bacteria.

Glycerin has also been found to have antimicrobial and antiviral properties. Due to these properties, glycerin is often used in wound and burn treatments.

In cosmetics, glycerin is usually derived from plants such as soybean or palm. However, it can also be sourced from animals, such as tallow or animal fat.

This ingredient is organic, colorless, odorless, and non-toxic.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

Learn more about Glycerin
Masking, Skin Conditioning

Citrus Aurantium Dulcis Fruit Extract is more commonly known as the bitter orange. Native to Southeast Asia, this extract is commonly found in both cosmetics and foods.

The bitter orange possesses antibacterial and antioxidant properties.

It can also be mildly exfoliating due to the citric acid, an AHA.

Citrus fruits are rich in flavonoids, alkaloids, and vitamin C.

Learn more about Citrus Aurantium Dulcis Fruit Extract
Masking, Skin Conditioning

Citrus Limon Fruit Extract comes from lemons. While lemon extract is exfoliating and antimicrobial, it can also cause skin sensitivity.

Lemons contains antioxidants, which may help with anti-aging. They are also rich in citric acid, an AHA.

And of course, lemons are rich in Vitamin C. Vitamin C helps with skin-brightening and increasing collagen production.

The acidity of lemons may work as an astringent for acne.

However, lemons can also cause skin sensitivity due to its limonene content. It can also increase photosensitivity, or sensitivity to the sun.

This ingredient is also used to add a lemon scent to products.

Learn more about Citrus Limon Fruit Extract
Skin Conditioning

Sodium levulinate is the a sodium salt of Levulinic Acid. If dissolved in an aqueous solution, the two ingredients become identical.

It is a skin conditioning agent, meaning it helps soften and hydrate your skin.

According to Cosmetic Ingredient Review, the highest amounts of sodium levulinate are found in mouthwashes at 0.62%.

Learn more about Sodium Levulinate
Skin Conditioning

We don't have a description for Acer Saccharum Extract yet.

We don't have a description for Diutan Gum yet.

Abrasive, Skin Conditioning

Tea tree leaves have antioxidant, anti-inflammatory, and antimicrobial properties.

Antimicrobial

Sodium Anisate comes from fennel. It is used as a preservative and to add flavoring.

Sodium Anisate has antimicrobial properties.

Skin Conditioning

We don't have a description for Mentha Australis Leaf Extract yet.

Humectant, Masking, Skin Conditioning

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

  • It is a solvent, meaning that it helps to dissolve other ingredients. This also enhances the absorption of the product into one's skin.
  • It is a humectant, which means that it helps attract moisture into the skin.
  • It helps improve product application.
  • It has mild preservative properties.

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

Skin Conditioning

Santalum Spicatum Seed Oil is an oil.

Citrus Aurantium Dulcis Oil comes from the bitter orange, an orange native to Southeast Asia.

This orange is commonly used in cosmetics and food. It is a common ingredient for marmalade.

Citrus peels are often made up of mainly limonene, a fragrance with a citrus scent. They also contain flavonoids, which have anti-inflammatory properties.

Learn more about Citrus Aurantium Dulcis Oil

Citrus Aurantium Bergamia Leaf Oil is an oil.

Juniperus Mexicana Oil is an oil.

Masking, Perfuming

Pelargonium Graveolens Oil is the pressed oil of the Rose Geranium plant.

Rose Geranium contains antimicrobial, anti-inflammatory, and antioxidant properties. It has been shown to reduce bacteria and fungus. The antioxidants may help reduce the signs of aging, such as fine-lines and wrinkles.

Fragrant components of Rose Geranium include citronellol and geraniol. These may cause allergies and skin-sensitivity. We recommend speaking with a professional if you have any concerns. The scent of Rose Geranium closely resembles traditional roses.

Learn more about Pelargonium Graveolens Oil
Masking, Skin Conditioning

Citrus Aurantium Amara Flower Oil is the volatile oil obtained from the flowers of the Bitter Orange, Citrus aurantium L. var. amara L., Rutaceae

Masking, Perfuming, Skin Conditioning

Eugenia Caryophyllus Leaf Oil is a fragrance and is an oil. It can cause irritation.

Citrus Aurantium Bergamia Fruit Oil is the oil from the bergamot orange. It is native to Italy.

This ingredient is used to add fragrance to products. It contains limonene, linalool, and linalyl acetate.

The term '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.

When used topically, Citrus Aurantium Bergamia Fruit Oil is a photosensitizer due to its furanocoumarins. Photosensitizers make the skin and eyes much more sensitive to sunlight. Photosensitizers are linked to skin cancer.

However, more cosmetics using Citrus Aurantium Bergamia Fruit Oil are removing the furanocoumarins.

Bergamot oil was also found to have anti-inflammatory, antibacterial and antifungal properties.

Learn more about Citrus Aurantium Bergamia Fruit Oil
Masking, Perfuming, Skin Conditioning

Citrus Grandis Peel Oil is an essential oil that is derived from the peel of a Grapefruit. It is composed largely of limonene, which is a fragrance that can cause irritation for sensitive skin.

Masking, Perfuming, Skin Conditioning

Citrus Limon Peel Oil is created from the peels of the lemon. It is used to add a lemon-scent to products. Lemon peel oil also has antibacterial, antifungal, and antioxidant properties. However, it may also cause phototoxicity and sensitize skin.

Lemon peel oil contains limonene, a skin sensitizing ingredient. Another component is furanocoumarin, which induces phototoxicity in skin.

Furanocoumarins bind and destabilize your DNA to increase the rate of sunburn.

Most reputable companies will remove furanocoumarins from their formulations.

Learn more about Citrus Limon Peel Oil
Masking, Perfuming, Tonic

Litsea Cubeba Fruit Oil is a fragrance and is an oil.

Skin Conditioning, Solvent

Pentylene glycol is typically used within a product to thicken it. It also adds a smooth, soft, and moisturizing feel to the product. It is naturally found in plants such as sugar beets.

The hydrophilic trait of Pentylene Glycol makes it a humectant. As a humectant, Pentylene Glycol helps draw moisture from the air to your skin. This can help keep your skin hydrated.

This property also makes Pentylene Glycol a great texture enhancer. It can also help thicken or stabilize a product.

Pentylene Glycol also acts as a mild preservative and helps to keep a product microbe-free.

Some people may experience mild eye and skin irritation from Pentylene Glycol. We always recommend speaking with a professional about using this ingredient in your routine.

Pentylene Glycol has a low molecular weight and is part of the 1,2-glycol family.

Learn more about Pentylene Glycol
Skin Conditioning

We don't have a description for Magnesium Aspartate yet.

Skin Conditioning

Zinc gluconate has antibacterial and wound healing properties. It is particularly effective against fighting inflammatory acne.

This ingredient is the zinc salt of the PHA gluconic acid. PHAs are gentle cousins to AHAs.

Antioxidant, Humectant, Skin Conditioning

Citrus Australasica Fruit Extract is an antioxidant.

Masking, Preservative

Sodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.

Both the US FDA and EU Health Committee have approved the use of sodium benzoate. In the US, levels of 0.1% (of the total product) are allowed.

Sodium benzoate works as a preservative by inhibiting the growth of bacteria inside of cells. It prevents the cell from fermenting a type of sugar using an enzyme called phosphofructokinase.

It is the salt of benzoic acid. Foods containing sodium benzoate include soda, salad dressings, condiments, fruit juices, wines, and snack foods.

Studies for using ascorbic acid and sodium benzoate in cosmetics are lacking, especially in skincare routines with multiple steps.

We always recommend speaking with a professional, such as a dermatologist, if you have any concerns.

Learn more about Sodium Benzoate
Buffering, Masking

Citric Acid is an AHA derived from citrus fruits (think oranges, lemons, and limes!).

As an AHA, Citric Acid removes the top layer of skin cells from the newer layer of skin underneath. This helps skin to remove dark spots and even out skin tone.

If you spot Citric Acid near the end of an ingredient list, it's likely there as a pH adjuster rather than an active ingredient.

Read more about some other popular AHA's here:

Learn more about Citric Acid
Skin Conditioning, Skin Protecting

This ingredient is a copper salt known for its wound healing properties.

Our bodies use copper to help stabilize our skin's collagen and elastin. Its also an essential for superoxide dismutase, an enzyme with strong antioxidant properties.

Copper has wound healing properties due to its role in creating new blood vessels and tissue repair.

Learn more about Copper Gluconate
Preservative

Potassium Sorbate is a preservative used to prevent yeast and mold in products. It is commonly found in both cosmetic and food products.

This ingredient comes from potassium salt derived from sorbic acid. Sorbic acid is a natural antibiotic and effective against fungus.

Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.

You'll often find this ingredient used with other preservatives.

Learn more about Potassium Sorbate
Buffering, Skin Conditioning

This ingredient is an amino acid that helps build proteins and moisturizes skin. It is already present in our skin as our bodies produce them naturally.

Glycine already plays a role in helping keep our skin moisturized as amino acids transport moisture throughout our skin.

As collagen is made up of glycine and other amino acids, it is believed glycine may help our skin produce more collagen.

Learn more about Glycine
Masking, Skin Conditioning

Serine is an amino acid naturally found in our body. Our bodies use amino acids to create protein.

Amino-acids help give keep our skin hydrated. They play an important role in the skin barrier, which keeps the skin plump and firm.

Serine is a non-essential amino acid, meaning we don't need to obtain it from eating foods.

Learn more about Serine
Humectant

Glutamic Acid is an amino acid that is found in all living organisms. Our bodies use this to help nerve cells in the brain communicate with other cells.

In cosmetics, glutamic acid is a famous humectant. It draws water from the air to your skin, keeping your skin hydrated (like hyaluronic acid).

An in-vitro study from 2024 found glutamic acid to play a role in inhibiting inflammation and thus a potential skin-soothing ingredient.

Other studies show it to be have potential wound healing, skin barrier repair, and hair growth properties.

Glutamic acid has poor solubility in water and other solvents.

Learn more about Glutamic Acid
Masking, Skin Conditioning

Aspartic Acid is an amino acid that our bodies produce naturally. It is an antioxidant.

Our body uses Aspartic Acid to help build collagen and elastin. It also plays a role in hydrating skin.

Skin Conditioning

We don't have a description for Leucine yet.

Masking, Skin Conditioning

Alanine is an amino acid and is already found in the human body. Our skin uses alanine to build collagen, elastin, and keratin.

Skin Conditioning

Lysine is an essential amino acid. Your body is unable to produce it naturally and we mainly get lysine from food sources.

Our bodies use lysine for growth and tissue repair. The skin uses amino acids as a precursor for building protein, and therefore keratins, collagen and elastin.

Masking, Skin Conditioning

Arginine is an amino acid that is important for human development. Your body uses is it to produce hair keratin and skin collagen.

As a cosmetic ingredient, Arginine has antioxidant properties and can also help repair damaged skin. This ingredient is derived either synthetically or from animals.

Arginine isn't fungal acne safe when used in the presence of other lipids (fats, fatty acids, oils, esters, etc). Oils and fats occur naturally within the skin, so take caution when using Arginine if you're prone to fungal acne.

Learn more about Arginine
Masking, Skin Conditioning

Tyrosine is one of the amino acids used to create protein. It plays a role in melanin production.

A study from 2012 found tyrosine to show promising results in restoring skin volume.

Masking, Skin Conditioning

Phenylalanine is an amino acid. It is a skin soothing and hydrating ingredient. Amino acids play a crucial role in wound healing and skin hydration.

This ingredient is also used to help even out skin tone due to its ability to disrupt the melanin production process.

Two structures of phenylalanine exist: L-phenylalanine and D-phenylalanine. L-phenylalanine is essential, this means our bodies cannot produce it naturally and we must get it from foods. Our bodies convert D-phenylalanine to neurotransmitters, and D-phenylalanine is found in our bodies naturally.

Some foods that contain L-phenylalanine include eggs, soybeans, beef, milk.

Learn more about Phenylalanine
Skin Conditioning

Proline is an amino-acid. It helps moisturize the skin and plays an important role in creating proteins.

Our skin uses proline as one of the building blocks for producing collagen.

In medicine, proline is used as an osmoprotectant. This means it helps prevent oxidative degradation in other drugs.

Our bodies are able to produce proline naturally, but certain conditions may inhibit this production. In that case, proline can be obtained from eating egg whites, soy protein, dairy products, asparagus, mushrooms, and seaweed.

Learn more about Proline

Threonine is an amino-acid. It helps hydrate the skin and has antioxidant benefits.

Our skin uses threonine for creating collagen and elastin. Humans are not able to create threonine and must get it through eating foods such as fish, lentils, poultry, sesame seeds, and more.

Masking, Skin Conditioning

Valine is an essential amino acid. It is used by our bodies for tissue repair and muscle growth.

An essential amino acid is one in which our bodies cannot naturally produce so we must get them through diet. Foods such as eggs, dairy, red meat, and fish contain valine.

This ingredient can either be derived from an animal product or be synthetically created.

Learn more about Valine
Skin Conditioning

Isoleucine is an amino acid that helps reinforce our skin barrier. This amino acid plays a role in creating protein for the body.

Fun fact: Isoleucine is found in meat, fish, dairy, legumes, and nuts.

Humectant, Skin Conditioning

Histidine is a semi-essential amino acid used by our bodies to create protein. It has humectant and skin conditioning properties.

Our bodies use histidine to create filaggrin - filaggrin is a structural protein that the skin uses in maintaining skin barrier.

One study found histidine and carnosine to be a dynamic duo for your skin:

Oral histidine has also been found to help with filaggrin-deficit skin disorders such as atopic dermatitis.

Why is it considered a semi-essential amino acid? This is because adults are able to create it but children must get it from their diet.

Learn more about Histidine
Perfuming, Solvent

Limonene is a fragrance that adds scent and taste to a formulation.

It's found in the peel oil of citrus fruits and other plants such as lavender and eucalyptus. The scent of limonene is generally described as "sweet citrus".

Limonene acts as an antioxidant, meaning it helps neutralize free radicals.

When exposed to air, oxidized limonene may sensitize the skin. Because of this, limonene is often avoided by people with sensitive skin.

The term '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.

Learn more about Limonene
Perfuming

Citral is a fragrance and used to add a lemon-like scent to products. It is both naturally found in plants and created synthetically. In plants, it is commonly occurring in lemon myrtle, lemongrass, lemon tea-tree, lemon verbena, and other citruses.

The EU mandates Citral be listed separately as a fragrance. It is a known allergen and may cause contact dermatitis. Citral can also used as a masking ingredient.

The term '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.

The term 'citral' is a collective term for two geometric isomers: geranial/Citral A and neral/Citral B.

Learn more about Citral
Perfuming

Linalool is a fragrance and helps add scent to products. It's derived from common plants such as cinnamon, mint, citrus, and lavender.

Like Limonene, this ingredient oxidizes when exposed to air. Oxidized linalool can cause allergies and skin sensitivity.

This ingredient has a scent that is floral, spicy tropical, and citrus-like.

Learn more about Linalool
Perfuming

Citronellol is used to add fragrance/parfum to a product. It is often derived from plants such as roses. In fact, it can be found in many essential oils including geranium, lavender, neroli, and more. The scent of Citronellol is often described as "fresh, grassy, and citrus-like".

Since the Citronellol molecule is already unstable, Citronellol becomes irritating on the skin when exposed to air.

Citronellol is a modified terpene. Terpenes are unsaturated hydrocarbons found in plants. They make up the primary part of essential oils.

Citronellol is not able to be absorbed into deeper layers of the skin. It has low permeability,

Citronellol is also a natural insect repellent.

Learn more about Citronellol

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Where it's from

Rationale is a Australian brand

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· Published May 13, 2024 Added by Niaaa