Liquid paraffin, often referred to as mineral oil, is a highly refined petroleum by-product used across various industries, from medicine to cosmetics. It is valued because it is colorless, odorless, and chemically stable. Modern, highly purified forms have made it a common fixture in healthcare and personal care routines.
Defining Liquid Paraffin and Its Grades
Liquid paraffin is a transparent, oily liquid composed of saturated hydrocarbons derived from the distillation of crude petroleum. The extensive refining process removes impurities, including aromatic compounds, sulfur, and nitrogen, resulting in a product that is inert and safe for human contact in its purified state. The quality and intended use of liquid paraffin are determined by its grade, which reflects the level of refinement it has undergone.
Pharmaceutical and cosmetic grades represent the highest level of purity, adhering to strict pharmacopoeia standards to ensure safety for internal consumption or topical application. This highly refined product is often called white oil or mineral oil. Conversely, industrial-grade liquid paraffin is less refined and is reserved for uses like machinery lubrication, which do not require the same level of purity.
Liquid paraffin is also classified by its viscosity, generally categorized as “light” or “heavy” liquid paraffin. Light liquid paraffin (paraffinum perliquidum) is a less viscous form often preferred in cosmetic formulations for its texture. Heavy liquid paraffin (paraffinum subliquidum) is the thicker variant typically chosen for its lubricating action in internal medical applications.
Topical Applications in Skin and Hair Care
In cosmetic and dermatological preparations, liquid paraffin functions primarily as an occlusive agent, forming a physical barrier on the skin’s surface. This thin layer prevents transepidermal water loss (TEWL), which is the evaporation of moisture from the skin into the air. By sealing the skin, it helps to keep underlying tissues hydrated and maintains the skin’s natural barrier function.
It is highly effective in managing dry skin conditions, such as eczema, psoriasis, and xerosis, where the skin barrier is compromised. It acts as an emollient, softening the skin and reducing associated scaling, itching, and irritation. Liquid paraffin is a common component in moisturizing creams, lotions, and baby care products due to its mildness and ability to soothe sensitive skin.
A common concern about liquid paraffin is its potential to clog pores, but highly refined pharmaceutical-grade versions are generally considered non-comedogenic for most individuals. In hair care, its occlusive properties add shine and reduce frizz by smoothing the hair cuticle and preventing moisture loss from the hair shaft.
Internal Use as a Laxative
Heavy liquid paraffin serves a distinct medical purpose as a lubricant laxative for the treatment of chronic constipation. When ingested, the oil passes largely undigested through the gastrointestinal tract due to its inert chemical nature. Its mechanism of action involves physically coating the intestinal wall and penetrating the fecal mass.
This coating prevents the reabsorption of water from the stool, keeping it soft and voluminous. Simultaneously, the oil acts as a lubricant, reducing friction and allowing the stool to pass more easily through the colon and rectum. This lubricating effect is especially beneficial for patients with anorectal conditions like hemorrhoids or anal fissures, as it minimizes straining during bowel movements.
Dosage is often titrated to achieve a soft stool consistency, and it is frequently recommended to be taken at night, away from mealtimes. While effective, its use is usually intended for short-term management. Long-term use is typically discouraged due to concerns about the potential for systemic absorption of the oil and interference with nutrient uptake.
Safety Considerations and Proper Handling
While highly refined liquid paraffin is considered safe for its intended uses, the most serious risk associated with internal administration is aspiration. Aspiration is the accidental inhalation of the oil into the lungs. Because the oil is inert, it is not broken down by lung tissue and can cause lipoid pneumonia.
This risk of aspiration is heightened in certain populations, particularly young children, the elderly, or patients with difficulty swallowing or pre-existing neurological impairments. Due to this danger, liquid paraffin should never be administered to individuals who are lying down or who have a compromised gag reflex.
Another precaution for oral use is the potential for the oil to interfere with the absorption of fat-soluble vitamins, specifically vitamins A, D, E, and K. When used topically, liquid paraffin is gentle, but rare instances of minor skin irritation or sensitivity may occur in susceptible individuals.