Methoxy Peg-114/Polyepsilon Caprolactone: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: July 1, 2025
Share:
Inside this article:

We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Methoxy Peg-114/Polyepsilon Caprolactone?

Methoxy Peg-114/Polyepsilon Caprolactone is a lab-made polymer that links together two well-known building blocks: polyethylene glycol (PEG) and polycaprolactone. PEG brings water-loving qualities while polycaprolactone adds a silky, flexible backbone. Chemists describe it as methylpoly(oxyethylene)poly(oxy-1-oxohexylene)ol with an average of 114 ethylene oxide units, but all that means is it has many small repeating parts that give it special texture and stability.

The ingredient does not come from plants or animals. Instead, producers start with simple petrochemical feedstocks, turn them into ethylene oxide, then build long PEG chains. These chains are joined with caprolactone units through ring-opening polymerization, a well-established process that lets scientists control chain length and performance. Finally, a methoxy group caps one end to keep the polymer from reacting further and to fine-tune how it feels on skin and hair.

PEG-based polymers entered the cosmetic world in the 1950s for their ability to dissolve in water and stay gentle on skin. By blending PEG with caprolactone, formulators unlocked added smoothness and film-forming power. Methoxy Peg-114/Polyepsilon Caprolactone began appearing in the early 2000s as brands looked for lightweight conditioners that leave no heavy residue yet still protect the skin barrier.

You will mostly see this ingredient in rinse-off and leave-on hair conditioners, styling creams, sheet masks, lightweight moisturizers, anti-aging serums and spray-on treatments where a soft, breathable film is helpful.

Methoxy Peg-114/Polyepsilon Caprolactone’s Cosmetic Benefits/Uses

Formulators choose Methoxy Peg-114/Polyepsilon Caprolactone for three main reasons

  • Buffering: Helps keep the product’s pH stable so the formula stays gentle and effective from the first use to the last
  • Film Forming: Creates a thin flexible layer on skin or hair that locks in moisture reduces transepidermal water loss and offers a smooth soft finish without a greasy feel
  • Hair Conditioning: Detangles strands adds slip and improves manageability making hair feel silky and look shinier

Who Can Use Methoxy Peg-114/Polyepsilon Caprolactone

This ingredient is generally well tolerated by all skin types including dry oily combination and sensitive skin because the large polymer molecules stay on the surface and do not clog pores or disrupt the barrier. People with a known allergy to PEGs or other synthetic polymers should steer clear as they might react even to the low-risk varieties.

Methoxy Peg-114/Polyepsilon Caprolactone is produced entirely from petrochemical feedstocks with no animal-derived starting materials or by-products which makes it suitable for vegans and vegetarians.

Current safety data show no reproductive toxicity and the polymer’s size means it is unlikely to penetrate deeply. Pregnant or breastfeeding individuals can usually use products containing it; however this is not medical advice and anyone expecting or nursing should check with a healthcare professional before adding new skincare to their routine.

The ingredient does not cause photosensitivity so it will not make skin more prone to sunburn. It can be used day or night and plays nicely with common actives like vitamin C retinol and niacinamide. As with any film former using very heavy layers may leave a slight residue that rinses off with normal cleansing.

Potential Side Effects/Adverse Reactions

Side effects from topical Methoxy Peg-114/Polyepsilon Caprolactone vary from person to person. The issues listed below are possible yet unlikely for most users when the ingredient is used at normal cosmetic levels

  • Mild skin irritation redness or itching can occur in individuals with very sensitive skin or compromised barriers
  • Allergic contact dermatitis rare cases of PEG sensitivity may lead to rash hives or swelling
  • Eye stinging if the product accidentally gets into the eyes temporary discomfort or watering may follow
  • Product buildup on hair excessive use in leave-on hair treatments can leave strands feeling coated or heavy until washed out

If any persistent burning swelling or rash develops discontinue use immediately and seek advice from a medical professional

Comedogenic Rating

Rating: 0–1 (very low)

Methoxy Peg-114/Polyepsilon Caprolactone is a large water-soluble polymer that sits on the skin surface then rinses away easily. Its molecular size keeps it from sinking into pores where clogs start and it leaves little oily residue. Because of these traits formulators rate it at 0–1 on the comedogenic scale.

That means it is generally suitable for people who are prone to acne or breakouts.

As always the full formula matters: if the product also contains heavy oils or waxes the overall likelihood of clogging could rise even though this single ingredient is low risk.

Summary

Methoxy Peg-114/Polyepsilon Caprolactone serves three main jobs in cosmetics: it buffers formulas to keep pH steady, forms a light breathable film that locks in moisture and conditions hair for easy detangling and added shine. It accomplishes these roles thanks to its blend of water-loving PEG segments and silky caprolactone blocks which spread smoothly and rinse clean.

The ingredient is not as common as classic PEGs yet its lightweight feel has gained interest in modern leave-on sprays, serums and conditioners that aim for a barely-there finish.

Current safety data show it is low irritation and non-sensitizing for most users. While it is considered safe always patch test a new product first to make sure it plays nicely with your unique skin.

Was this article helpful?
More from Glooshi:
ADVERTISEMENT
Get all our top headlines in beauty.
Delivered right to your inbox each week. Zero spam, all goodness, opt-out at anytime.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Get the latest beauty news, top product recommendations & brand-exclusive discount codes direct to your inbox.
Send good feedback:

All feedback is greatly appreciated, anonymous, and will be used to improve the quality of our articles.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Send bad feedback:

All feedback is greatly appreciated, anonymous, and will be used to improve the quality of our articles.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Search