What Is Oleth-45?
Oleth-45 is a liquid ingredient created by linking oleyl alcohol, a fatty alcohol usually sourced from plant oils like olive or sunflower, with about 45 units of ethylene oxide. This pairing turns the oily starting material into a water-friendly substance that can blend oil and water. Chemists developed this class of ingredients in the mid-20th century when the cosmetics industry was looking for gentler alternatives to traditional soaps. Production starts with purified oleyl alcohol, which is reacted with ethylene oxide in a controlled setting. The finished material is then filtered and quality-checked for use in personal care formulas.
You will most often see Oleth-45 in facial cleansers, liquid body washes, makeup removers, hair conditioners, lightweight lotions, sheet masks and rinse-off exfoliating treatments where a smooth, even texture is needed.
Oleth-45’s Cosmetic Benefits/Uses
In formulas, Oleth-45 serves two main jobs that help a product look, feel and work better:
- Cleansing: Its surfactant nature loosens dirt, oil and makeup so they can be rinsed away without harsh scrubbing, leaving skin or hair feeling fresh yet comfortable
- Emulsifying: It keeps oil and water mixed into a stable, uniform blend, which prevents separation and gives creams or washes a silky, consistent texture from the first pump to the last
Who Can Use Oleth-45
Oleth-45 is generally well tolerated by most skin types, including normal, oily, combination and even many sensitive skins because it is a mild cleansing and emulsifying agent that does not usually strip the surface of moisture. People with very reactive or allergy-prone skin should be cautious if they know they react to polyethylene glycols or fatty alcohol derivatives, as Oleth-45 belongs to those families.
Oleth-45 is usually suitable for vegans and vegetarians since the oleyl alcohol it starts from is most often sourced from plant oils like olive or sunflower. If you follow a strict plant-only lifestyle you may want to confirm the source with the brand to be sure it is not derived from animal fats.
The ingredient has no known issues for pregnant or breastfeeding women when used topically in rinse-off or leave-on cosmetics. This is not medical advice and anyone who is expecting or nursing should check with their healthcare provider before introducing new personal care products, just to be safe.
Oleth-45 does not increase photosensitivity, so it will not make skin more prone to sunburn. Regular sunscreen use is still advised as part of overall skin health.
Potential Side Effects/Adverse Reactions
Reactions to any cosmetic ingredient vary from person to person. The points below list potential side effects linked to topical use of Oleth-45, but most users will not experience them when the ingredient is used at normal levels in well-formulated products.
- Mild skin irritation – tingling, redness or a tight feeling, more likely in very sensitive or compromised skin
- Allergic contact dermatitis – rare cases of itching, rash or swelling if the user happens to be allergic to polyethylene glycol derivatives
- Eye irritation – temporary stinging or watering if a cleanser containing Oleth-45 gets into the eyes
- Scalp buildup – with heavy or frequent use in hair products some people may notice residue that can weigh hair down
If any discomfort or unusual reaction appears, discontinue use and consult a healthcare professional or dermatologist for guidance
Comedogenic Rating
Rating: 1 / 5
Oleth-45 scores low because its large PEG chain makes it highly water soluble so it rinses away easily and does not sit in pores the way heavier oils can. The oleyl part could be mildly clogging on its own, yet once it is turned into a PEG ether its occlusive potential drops sharply. Most formulas also use it at modest levels, further limiting any pore-blocking risk.
Overall, Oleth-45 is considered suitable for skin that is prone to acne or breakouts.
Because it is usually found in rinse-off cleansers rather than thick leave-on creams the real-world chance of it causing blackheads is very small.
Summary
Oleth-45 is a workhorse surfactant that cleanses by surrounding dirt and oil so water can lift them away and it emulsifies by keeping water and oil blended for a smooth stable texture. Its balance of a fatty tail and a long water-loving PEG chain lets it glide between the two phases and hold them together.
While not a headline ingredient it shows up quietly in many everyday cleansers lotions and hair products because formulators value its mildness and reliability.
Safety reviews find it non-sensitising for most people and the low comedogenic rating makes it a low-risk option for acne-prone users. Still, skin can be unpredictable so it is smart to patch test any new product that contains Oleth-45 before full use.