Which nonionic surfactant is commonly used in topical emulsions?

• A. Polysorbate 80
• B. Sodium lauryl sulfate
• C. Cetyltrimethylammonium chloride
• D. Stearic acid

Answer: (A)

Nonionic surfactants are often preferred in topical emulsions because they tend to be milder on skin and versatile across ingredients. Polysorbate 80 (Tween 80) is a classic nonionic surfactant with a high HLB value around 15, making it effective for stabilizing oil-in-water systems typical in creams and lotions. It helps solubilize oils and active ingredients while forming a stable emulsion without introducing charge-related interactions, which reduces irritation and compatibility issues.

In contrast, sodium lauryl sulfate is an anionic surfactant that can irritate the skin and create stability problems in some topical formulations. Cetyltrimethylammonium chloride is cationic and can interact with skin proteins and other formulation components in ways that raise irritation or compatibility concerns. Stearic acid is a fatty acid and, while it contributes to thickening and emollience, it is not a nonionic surfactant used as the primary emulsifier in topical emulsions.