Peg-20 Evening Primrose Glycerides: 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
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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 Peg-20 Evening Primrose Glycerides?

Peg-20 Evening Primrose Glycerides is a plant-derived ingredient made from evening primrose (Oenothera biennis) seed oil. Chemically, it consists of mono- and diglycerides from the oil that have been linked with an average of twenty ethylene oxide units, which turns the fatty part of the oil into a water-compatible form. This gives formulators a way to bring the soothing lipid profile of evening primrose into products that contain water.

Evening primrose oil has been prized for its skin-comforting properties since the 1970s and chemists soon looked for ways to fit it into modern lotions without leaving a greasy feel. By the late 1990s, the ethoxylation process had become reliable enough to create Peg-20 versions of many plant oils, and the evening primrose form quickly found a place in gentle skincare meant for sensitive complexions.

Manufacturing starts with cold-pressing the seeds to collect the raw oil. The oil is then reacted with glycerol to form mono- and diglycerides, which are more stable. These glycerides go through controlled ethoxylation, adding about twenty ethylene oxide units to each molecule. The final step is purification to remove excess reactants and ensure a clear, pourable liquid that blends easily in water-based formulas.

You will typically see Peg-20 Evening Primrose Glycerides in moisturizers, lightweight creams, milky cleansers, sheet mask essences, baby lotions, after-sun gels and hair conditioning treatments where a gentle plant-based emulsifier is preferred.

Peg-20 Evening Primrose Glycerides’s Cosmetic Benefits/Uses

This ingredient is valued mainly for one key function that improves both the feel and stability of many personal care products.

Emulsifying: Peg-20 Evening Primrose Glycerides helps oil and water mix evenly so the product stays smooth from the first pump to the last drop. A stable emulsion prevents separation, improves shelf life, creates a lighter texture and allows nourishing oils to be delivered without a heavy residue.

Who Can Use Peg-20 Evening Primrose Glycerides

Because it is a mild plant-based emulsifier Peg-20 Evening Primrose Glycerides generally suits all skin types including dry, normal, combination, oily and sensitive. It is lightweight so even sebum-rich or breakout-prone skin usually tolerates it well, though people who react to any polyethylene glycol derivative should steer clear.

The ingredient is sourced from evening primrose seed oil and glycerin, both of which are plant derived, so it is appropriate for vegans and vegetarians and involves no animal testing or animal by-products in its manufacture.

There is nothing in its chemistry that is known to pose a risk during pregnancy or while breastfeeding when used on the skin. This is not medical advice and anyone who is pregnant or nursing should show the full product ingredient list to a qualified healthcare professional before use, just to be safe.

Peg-20 Evening Primrose Glycerides is not photosensitising, meaning it will not make skin more sensitive to sunlight. It is also fragrance-free and carries no natural colorants, so it will not tint the skin or fabric.

Potential Side Effects/Adverse Reactions

Responses to any cosmetic ingredient can differ from person to person. The issues below are only potential side effects and are uncommon when the ingredient is used correctly in a finished formula.

  • Mild irritation or redness in very sensitive skin
  • Allergic contact dermatitis in individuals allergic to polyethylene glycol derivatives
  • Transient stinging if applied to broken or freshly exfoliated skin
  • Temporary eye discomfort if the product accidentally gets into the eyes
  • Rare pore congestion in users who are highly prone to comedones

If any of these reactions occur stop using the product immediately and seek advice from a healthcare professional.

Comedogenic Rating

Rating: 1 / 5

Peg-20 Evening Primrose Glycerides is largely water dispersible thanks to its ethoxylated structure so it rinses away more easily than pure oils. It contains only small amounts of the original evening primrose fatty acids which lowers its tendency to linger in pores. For these reasons it sits at the lower end of the scale with a score of 1.

This makes the ingredient generally suitable for acne-prone or breakout-prone skin when used in the low percentages typical of finished products. As with any emulsifier final comedogenicity also depends on the entire formula, concentration and how thoroughly the product is removed.

Summary

Peg-20 Evening Primrose Glycerides is a plant based emulsifier that lets oil and water stay perfectly blended, giving creams and cleansers a smooth, lightweight feel while delivering the soothing lipids of evening primrose oil. It performs by surrounding oil droplets with its PEG side for water affinity and its glyceride side for oil affinity, keeping the mixture stable during use and storage.

The ingredient enjoys moderate popularity in gentle skincare lines, baby care and after-sun products where formulators want a mild non-sticky texture drawn from natural sources. It is not as widespread as classic PEG-40 hydrogenated castor oil yet is well regarded by brands favoring botanically inspired emulsifiers.

Safety evaluations classify it as low risk for irritation or sensitization when used as directed. Still, individual skin responses can vary so it is smart to patch test any new product that contains Peg-20 Evening Primrose Glycerides before full use.

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