Ingredient · Multipurpose Carrier + Humectant
Butylene Glycol (1,3-Butanediol)
INCI · Butylene Glycol
Related names and forms: 1,3-Butanediol · 1,3-Butylene Glycol. This list does not indicate synonyms or exact ingredient matches.
Butylene glycol (1,3-butanediol, or 1,3-BG) is one of the most versatile cosmetic formulation ingredients. It can work in three roles at once: solvent, carrier and light humectant. This versatility explains why formulation teams favour it particularly in multi-active serums and lightly textured essences. In the Turkish market, butylene glycol frequently appears among the first 3-5 ingredients of Korean and Japanese K-Beauty / J-Beauty serums. Formulation traditions in these regions support a light, layered approach to care, and butylene glycol provides its carrier foundation. For Klaris, its position offers a reading cue: within the first 5 ingredients, it signals a formula aiming for a light, fluid texture; in the middle or at the end, it plays a secondary supporting role. It should not be confused with propylene glycol. These are different molecules: butylene glycol has a 4-carbon chain and propylene glycol a 3-carbon chain, and their skin behaviour differs. Butylene glycol is generally associated with fewer irritation reports than propylene glycol, a difference frequently emphasised in sensitive-profile messaging. Specifically vetted clinical dermatology research on butylene glycol is limited; most information comes from formulation chemistry and CIR safety assessment reports.
i. Cosmetic Functions
Frequently Discussed Effects
The following headings summarise areas of effect frequently discussed in the literature; visible results in each area require regular use and a suitable formula.
A Multipurpose Solvent
It works as a bridging solvent to stabilise both water-soluble and fat-soluble actives in a formula.
A Light Humectant
Its moisture-attracting profile is modest, not as strong as glycerin or hyaluronic acid, but it provides a supporting foundation.
Texture Adjustment
It adds lightness and fluidity, making it a choice for low-viscosity products such as serums and essences.
Mechanism
What Happens Within the Skin?
The following points summarise mechanisms from dermocosmetic literature in plain English. Klaris presents them as background information to help readers understand the context, not as medical claims.
Step 1
Solvent Action Across Two Phases
Butylene glycol has both polar properties (hydroxyl groups) and relatively non-polar properties (a 4-carbon chain), making it an effective solvent bridging hydrophilic and lipophilic ingredients.
Step 2
Light Moisture Attraction
Its two hydroxyl groups bind water molecules in the air and upper skin layers, but its moisture-attracting strength is lower than that of glycerin or propanediol.
Step 3
Stratum Corneum Penetration Support
Some in vitro studies show that butylene glycol can temporarily loosen lipid layers in the stratum corneum, which may support penetration by other actives in the formula.
Step 4
Antimicrobial Support
At high concentrations (>5%), butylene glycol can reduce preservative requirements. It is not a standalone preservative, but an ingredient that enhances the preservative system.
ii. Role in the Formula
How Is It Read on a Label?
Butylene glycol is generally used at 3% - 15% across a wide range of categories. It is common in essences, toners, light serums, light creams and primers. Compatibility in combined use cannot be guaranteed from ingredient names alone; the product formula and conditions of use must be considered together.
A Closer Look · pH, Stability, Synergy
Butylene glycol is one of the most practical formulation ingredients: stable, pH-flexible and multipurpose. Its range is broad (3% - 15%): low levels (3-5%) act as a solvent for botanical extracts or fat-soluble actives, medium levels (5-10%) as the main carrier foundation, and high levels (10-15%) as the primary liquid phase in rich essences or light serums. Most formulas pair it with glycerin, which establishes the main humectant foundation while butylene glycol provides a light carrier layer. This combination is a classic formulation signature of Asian serums. Its mild antimicrobial support can reduce the need for parabens or other preservatives in high-concentration formulas; some brands using "paraben-free" messaging deliberately keep butylene glycol levels high. Longer-chain alternatives such as pentylene glycol and hexylene glycol also exist. These offer stronger antimicrobial support than butylene glycol but cost more and can receive rare irritation reports in sensitive skin. Butylene glycol works with other humectants such as glycerin, propanediol, hyaluronic acid and sodium PCA and is a common part of the modern "multi-humectant" approach. Compatibility in combined use cannot be guaranteed from ingredient names alone; the product formula and conditions of use must be considered together. There is no specific warning for topical butylene glycol during pregnancy. It also appears in hair care, attracting moisture and lightly adjusting texture in shampoos, balms and serums.
Typical Concentration Range
3% - 15% (depending on formula type)
Ingredient Family
Humectants
iii. Sensitivity Advisory
A Note on Extra Care in Context
Butylene glycol is well tolerated by most skin profiles, and allergic contact dermatitis is rare. A patch test may be useful for profiles with known glycol-derivative sensitivity.
A sensitivity advisory is not an instruction for use; where individual health circumstances, pregnancy or known sensitivities are involved, discussing the decision with your doctor may be a more contextual approach.
Common Misconceptions
Frequently Confused Points
Common Belief
Butylene glycol and propylene glycol are the same ingredient under different names.
A More Contextual Reading
They are different molecules: butylene glycol has a 4-carbon chain (1,3-butanediol), while propylene glycol has a 3-carbon chain (1,2-propanediol). Their skin behaviour differs, and butylene glycol is generally associated with fewer irritation reports.
Common Belief
Butylene glycol penetrates the skin and reaches internal organs.
A More Contextual Reading
Topical butylene glycol sits in the upper layers of the stratum corneum; there are no clinical data showing meaningful amounts entering systemic circulation. The claim that it "reaches internal organs" is not supported by independent scientific sources.
Common Belief
Butylene glycol is a beneficial humectant for dry skin.
A More Contextual Reading
Butylene glycol is a light humectant and may be insufficient on its own for dry skin. It may be useful to check that formulas for dry skin also contain stronger moisture-supporting foundations such as glycerin, hyaluronic acid or ceramides.
Scientific Basis
Sources and Their Scope
The following headings indicate areas of research; they are not citations of a specific publication or confirmation that every statement on this page has been verified. The links provided should be read with their individual scope in mind.
- International INCI / CosIng Database
- Regulatory Authority Documents (EU SCCS, TİTCK)
- Formulation Chemistry Guides
TİTCK, SCCS and similar regulatory authorities are mentioned in the context of publicly available regulation; Klaris has no official endorsement, partnership or collaboration with these institutions.
Starting Points for Independent Research
These links lead to official databases and serve as starting points for searches.
iv. Related Ingredients
Ingredients Often Read Together
v. Humectants Family
Other Ingredients in the Same Family
Explore ingredients in the same functional family to deepen your reading of formulas.
vi. Academy · Related Reading
For a Closer Look
Klaris · Example Analyses
How Does Butylene Glycol (1,3-Butanediol) Feature
in Your Products?
Explore product examples to see the ingredient list, general assessment and match score that changes with the example profile together.
Masked products and example profiles, not a personal analysis. Profile matching in the app is part of Klaris Premium. The app is currently available in Turkish. An English version is in preparation.