What Is C12-15 Alketh-5?
C12-15 Alketh-5 is a man-made ingredient created by attaching about five units of ethylene oxide to a blend of synthetic fatty alcohols that have carbon chain lengths between 12 and 15. These alcohols can be sourced from petroleum derivatives or from plant oils such as coconut or palm. The result is a waxy solid or thick liquid that mixes easily with both water and oil.
Chemists began adding ethoxylated fatty alcohols to personal care products in the late 1960s when the industry was looking for stable, versatile emulsifiers. Over time C12-15 Alketh-5 became popular because it offers reliable performance at a reasonable cost and works in a wide pH range.
To make it, manufacturers start with purified C12-15 fatty alcohols, react them with ethylene oxide gas under heat and pressure, then neutralize and refine the mixture. The “5” in the name tells formulators the average number of ethylene oxide units attached, which influences how well the ingredient balances oil and water.
You will find C12-15 Alketh-5 in many rinse-off and leave-on products. Common examples include facial cleansers, body washes, lightweight lotions, sunscreens, hair conditioners, makeup removers, clay or cream masks and some anti-aging serums that combine water-based actives with nourishing oils.
C12-15 Alketh-5’s Cosmetic Benefits/Uses
Its main job in skincare and haircare formulas is to keep oil and water perfectly blended.
Emulsifying: C12-15 Alketh-5 sits at the boundary between oily ingredients and watery ones. By lowering surface tension it helps create smooth, even emulsions so lotions do not separate and cleansers rinse away without leaving a greasy feel. This gives products a pleasant texture, improves spreadability and makes sure each application delivers the same level of active ingredients.
Who Can Use C12-15 Alketh-5
C12-15 Alketh-5 is generally well tolerated by most skin types, including oily, combination, normal and dry. Its lightweight feel and low residue make it suitable for acne-prone skin as well, since it will not clog pores on its own. People with very sensitive or compromised skin might notice mild irritation when using high concentrations, so they may want to look for products that pair it with soothing ingredients.
The ingredient itself is synthetic and can be sourced from either petroleum derivatives or plant oils. When made from coconut or palm oil and processed without animal by-products it is considered suitable for vegans and vegetarians. If a brand does not specify plant sourcing, those who avoid animal ingredients should confirm with the manufacturer.
No evidence suggests that C12-15 Alketh-5 poses a specific risk to pregnant or breastfeeding women when used topically in cosmetic amounts. Still, this is not medical advice and anyone who is pregnant or nursing should show their doctor any product they plan to use to stay on the safe side.
The ingredient does not increase photosensitivity, so it will not make skin more prone to sunburn. It also does not interfere with common actives such as vitamin C, niacinamide or retinoids, making it easy to layer within a routine.
Potential Side Effects/Adverse Reactions
Responses to topical C12-15 Alketh-5 vary from person to person. The points below outline potential side effects that could occur, but they are uncommon when the ingredient is used at standard cosmetic levels.
- Mild skin irritation – can show up as temporary redness or stinging in people with very reactive skin
- Contact dermatitis – rare allergic reaction that may include itching, swelling or small bumps
- Dryness – overuse in leave-on products might strip natural oils in those with already dry skin
- Eye irritation – possible if a cleanser or shampoo containing the ingredient gets into the eyes
If any of these effects occur stop using the product and seek guidance from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1 out of 5. Although the starting fatty alcohols are mid-chain and could be mildly comedogenic on their own, the addition of ethylene oxide units makes C12-15 Alketh-5 far more water soluble so it is unlikely to build up in pores. Most formulations use it at low levels simply to hold oil and water together, further reducing any clogging risk. In short, it is generally safe for people prone to acne or breakouts. Rinse-off products pose virtually no concern, while leave-on items remain low risk at typical use levels.
Because the ingredient is often paired with lightweight oils and silicones, the overall pore-clogging potential of the finished product depends on the rest of the formula rather than on C12-15 Alketh-5 itself.
Summary
C12-15 Alketh-5 is an emulsifier that helps water and oil stay blended, giving lotions, cleansers and sunscreens a smooth, even texture. It does this by lowering surface tension at the oil-water boundary so active ingredients are delivered consistently with every use.
The ingredient is a workhorse in modern cosmetics, popular with formulators who need a dependable, cost-effective emulsifier that functions across a wide pH range. You will spot it more often in mass-market and mid-range products than in luxury lines, mainly because it does its job quietly without adding sensory flair.
Safety data show it is well tolerated by most skin types, carries a very low risk of irritation and scores a 1 on the comedogenic scale. Still, everyone’s skin is different so it is wise to patch test any new product containing C12-15 Alketh-5 before making it a regular part of your routine.