What it is
Laureth-4 is a nonionic surfactant made by reacting lauryl alcohol with about four units of ethylene oxide. With its relatively low degree of ethoxylation it is fairly lipophilic, which makes it useful as a co-emulsifier and as an aid in dissolving oils into a formula. In sun care products it helps blend the oil and water phases and can support a smooth, uniform texture.
Safety & warnings
Laureth-4 is generally well tolerated in rinse-off and leave-on products at typical use levels. Because it is an ethoxylated surfactant, finished-ingredient quality matters, as ethoxylation can produce trace impurities that reputable suppliers control. It is not a fragrance allergen and is not classed as a comedogenic oil.
Origin & sourcing
Synthetic. It is produced by ethoxylating lauryl (dodecyl) alcohol, which itself may come from petrochemical or plant-derived sources such as coconut or palm.
Questions everyone asks
What does the number 4 mean in Laureth-4?
It indicates the average number of ethylene oxide units attached to the lauryl alcohol, which influences how oil-loving or water-loving the surfactant is.
Why is it used in sunscreens?
It works as a nonionic emulsifier and solubilizer, helping the oil and water parts of the formula mix into a stable, smooth product.