Baby oil is predominantly refined mineral oil. Most commercial baby oils are composed of 98% or more mineral oil, with the remainder typically consisting of fragrance. This colorless, odorless liquid serves as the primary functional ingredient and is a highly purified form of the substance known as liquid paraffin or white mineral oil. Baby oil is designed to be gentle and effective for moisturizing in both infant and adult skincare routines.
What Mineral Oil Is
Mineral oil used in cosmetic and pharmaceutical products is a highly refined hydrocarbon derived from petroleum. It is a byproduct of the crude oil refining process, but it is chemically distinct and far purer than the unrefined raw material. The cosmetic-grade oil, often referred to as “white mineral oil” or “liquid paraffin,” undergoes rigorous purification to remove aromatic compounds and other impurities.
The finished product is a clear, stable, and inert substance that is safe for topical application, meeting strict purity standards set for food and pharmaceutical grades. This refinement ensures the mineral oil is non-toxic, non-allergenic, and resistant to oxidation, meaning it will not spoil. Mineral oil is a mixture of long-chain aliphatic and cyclic hydrocarbons, categorized into light and heavy grades based on viscosity and density.
How Mineral Oil Works on Skin
Mineral oil functions primarily as an occlusive agent when applied to the skin. This means it forms a physical, non-permeable barrier on the skin’s surface, effectively sealing in moisture. This protective layer works to significantly reduce Transepidermal Water Loss (TEWL), which is the natural evaporation of water from the skin.
By reducing TEWL, the mineral oil helps increase the water content in the stratum corneum, the outermost layer of the skin, leading to improved hydration and barrier function. Studies indicate that mineral oil can reduce water loss by up to 30%, resulting in softer and smoother skin. Since the molecular size of the refined mineral oil is large, it does not penetrate the skin beyond the surface layer.
This lack of absorption is why highly purified mineral oil is considered non-comedogenic for most users; it sits on top of the skin and does not clog the pores. The occlusive properties make it beneficial for individuals with dry skin conditions or compromised skin barriers, such as those experiencing mild eczema. However, because it only seals in existing moisture and does not actively add hydration, it is most effective when applied to skin that is slightly damp.
Common Alternatives to Mineral Oil
Consumers seeking alternatives to mineral oil often look toward plant-derived options that offer similar moisturizing benefits. Jojoba oil is a popular substitute because its structure closely resembles the natural oils found in human skin, making it a highly compatible emollient. It also offers occlusive properties and is considered non-comedogenic, making it suitable for acne-prone skin.
Other plant-based alternatives include shea butter and coconut oil, which are rich in fatty acids and provide deep hydration and skin-softening effects. Shea butter is a luxurious emollient, while coconut oil is known for its anti-inflammatory properties, although its comedogenic rating means it may not be ideal for all skin types. Lightweight options like squalane, a plant-derived emollient that mimics the skin’s natural sebum, are also frequently used for their ability to lock in moisture without leaving a heavy residue.