Understanding the Role of Surfactants in Cosmetic and Cleaning Products (2025)

A surfactant (the shortened name for "surface-acting agent") is a chemical compound that changes how a liquid behaves. When a surfactant is added to a liquid, it reduces its surface tension. This allows the liquid to spread out and wet the surface to which it is applied.

Surfactants can increase the wetting, emulsifying (combining), foaming, and dissolving properties of liquids. They are commonly used in many personal, cosmetic, and cleaning products. While these compounds can improve a liquid's function, they can also pose safety concerns for people, animals, and the environment.

Role of Surfactants in Popular Products

Surfactants are added to common household products because they can improve the interaction of water with oily substances like grease and dirt. The roles of surfactants include the following.

1. Facilitate Cleansing

Surfactants help lift grease and dirt from surfaces when used in cleaning products such as laundry detergent, hand soap, shampoo, and dish soap. They enable cleansers to mix with water and stay in suspension (remain mixed) to remove dirt from the surface being cleaned. When the surfactant is rinsed away, the dirt and oils are removed with the water.

Without surfactants, soaps and detergents would separate from the water without mixing into it. This would interfere with the cleaning process.

2. Improve Wetting Properties

Surfactants also help a liquid disperse and wet a surface. This characteristic helps a cleanser or other liquid flow more smoothly so it can cover an entire surface for maximum effectiveness.

The ability of surfactants to facilitate a liquid's wetting properties is also important in the use of pesticides. The waxy surface of many fungi, insects, and plants can interfere with the ability of a water-based spray to penetrate these targets. Surfactants allow better penetration.

3. Promote Foaming

Surfactants provide significant benefits as foaming agents. Foam, rather than a liquid that can run off, helps distribute personal care products such as shampoos, facial cleansers, and bodywash so oil and dirt can be removed from the hair and skin. Users often prefer a foam formulation.

Foam is also valuable in industrial cleaners required to cover large surface areas. Foaming promotes better contact between the cleaning agent and dirt. The foaming properties of food-grade surfactants are also valuable in the food industry to produce mousses, whipped toppings, and meringues.

Foaming surfactants also improve the effectiveness of firefighting foams, which are used to prevent and extinguish fires. These compounds cut off oxygen to the fire and suppress it.

4. Improve Lubrication

Surfactants are a key ingredient in lubricants because they create a thin film between moving surfaces. For example, in shaving cream, foam allows razors to glide along the skin, removing stubble and reducing irritation.

When added to car engine lubricants, surfactants help keep particles from sticking to engine parts. This allows the parts to move as intended.

5. Facilitate Emulsification

Lotions and creams are emulsions (mixtures of oils and water that do not separate into their own layers). The oily material is combined with water and other ingredients to formulate a product that doesn't need remixing before you apply it.

Surfactants are used as emulsifiers to create oil-in-water (moisturizing lotions) or water-in-oil substances (moisturizing creams) and deliver the oils to your skin's surface.

Types of Surfactants

Surfactants break down the interface between water and oils and/or dirt, while also holding these oils and dirt in suspension for removal.

Surfactants can do this because they are compounds that contain both a hydrophilic (water-loving) end, where water molecules tend to congregate, and a hydrophobic (water-hating) end, where water-insoluble material such as oil and grease gather.

Surfactants are grouped based on the electrical charge of the hydrophilic group of molecules. Anionic and nonionic surfactants comprise the most commonly used surfactants.

Anionic Surfactants

Anionic surfactants have a negative charge on their hydrophilic end, which helps the substance lift and suspend materials like oil and dirt. These surfactants can improve foaming and other spreading properties. They are very strong cleaners often used in soaps and detergents.

Examples of anionic surfactants include:

• Ammonium lauryl sulfate
• Sodium laureth sulfate
• Sulfosuccinates
• Alkylbenzene sulfonate

Nonionic Surfactants

Nonionic surfactants do not have any charge on their hydrophilic end. They are neutral. These surfactants excel at emulsifying oils and perform better than anionic surfactants at removing organic soils. These surfactants typically have a low potential for irritation.

They are unique because they have a cloud point, which is the temperature at which they separate from the cleaning solution. Nonionic surfactants are commonly used in pharmaceutical products.

Examples of nonionic surfactants include:

• Alkyl ether
• Alkylglyceryl ether
• Polyoxy ethylene 4 lauryl ether
• Polyoxy ethyleneacetylethers

Cationic Surfactants

Cationic surfactants have a positive charge on their hydrophilic end. Since they are more irritating and don't clean, rinse, or foam as well as other surfactants, cationic surfactants are not used for cleaning.

However, they are ideal for conditioning and are often used as the primary ingredients in rinse-off hair conditioners. They also have strong disinfecting properties.

Examples of cationic surfactants include:

• Didecyldimethylammonium chloride
• Dodecyl trimethyl ammonium chloride
• Tetrabutylammonium chloride
• Benzalkonium chloride

Amphoteric Surfactants

Amphoteric surfactants are also referred to as zwitterionic materials. In these surfactants, the hydrophilic end may simultaneously carry both anionic and cationic hydrophilic groups depending on ambient conditions such as pH (a scale of acid to base).

They are often used in cleansing products such as shampoos. They can help thicken a formula and make a substance creamier with smaller bubbles.

Examples of amphoteric surfactants include:

• Cocamidopropyl betaine
• Cocoamphopropionate
• Sodium lauraminopropionate

Chemistry Simplified

Surfactants reduce the surface tension of water. Without surfactants, a drop of water retains its shape and will not spread on a surface. When surfactants are added to water, they help the water spread out and wet a treated surface, whether it's clothing, surface, hair, or dishes.

When a surfactant is combined with water, the hydrophobic (water-hating) ends work to stay away from the water. They organize into a spherical shape called a micelle. The water-loving ends remain on the outside of the micelle, and the water-hating ends, which don't want to be near water, remain protected on the inside of the micelle.

In liquid soaps and detergents, surfactants form a thin layer over substances such as dirt and grease on treated surfaces. Oil, dirt, and grease are hydrophobic substances attracted to the inside of the surfactant micelle after they are lifted off the treated surface.

These hydrophobic substances become suspended in the water in the micelle so they can't return to the surface. The soil is easier to wash away with water since it remains trapped in the micelle, which is suspended in water.

Safety Concerns

Surfactants have a range of applications in consumer and industrial products, including foods, cosmetics, healthcare products, and pesticides. While surfactants improve the performance of commonly used products, many of these compounds are synthetic products that pose the following health and environmental safety risks:

1. Damage to the Human Body

Surfactants in pharmaceutical and cosmetic products have been linked with skin reactions such as irritant contact dermatitis and inflammation. They also have some degree of toxicity.

After surfactants enter the body, they can damage the activity ofenzymes(proteins that facilitate chemical reactions) and disrupt normal body functions. They may also collect in the body, making it difficult to degrade their impact. However, the type of surfactant used and its mechanisms of action vary widely.

Generally, nonionic surfactants pose a lower risk of irritation to your skin, while cationic surfactants pose the largest risk. The toxicity of anionic surfactants runs between nonionic and cationic surfactants.

Research indicates that sodium dodecyl benzene sulfonate (which is used in detergents, cleaning products, and pesticides) can be absorbed through your skin. potentially causing liver damage. Other effects, such as developmental malformations in a fetus andcancer,have also been linked to this surfactant.

2. Polluted Wastewater

Large-scale use of surfactants has contributed to contaminated wastewater. In high concentrations, surfactants and the unwanted chemicals that can develop from their use are difficult to treat in wastewater.

The high concentration of surfactants from urban, industrial, and domestic wastewater increases the risk of contaminating drinking water, posing a further risk to humans and animals. Some surfactants have severe health implications for humans when ingesting or drinking contaminated food or water.

3. Damage to Aquatic Life

Depending on the concentration, surfactants in the water can affect algae growth and aquatic microbes. This can undermine the food chain of aquatic microbial organisms and harm fish and other aquatic life in water bodies.

The accumulation of surfactants can increase over time since synthetic surfactants have low biodegradability, meaning they are not easily broken down by natural substances like bacteria and fungi and reabsorbed in the environment.

Summary

Surfactants have widespread use in a range of consumer and industrial products. They are used to clean soil and other substances from skin, clothing, and household items. They work by breaking down the interface between water and dirt. They also hold the dirt in suspension, easing its removal in water.

Surfactants contain both hydrophilic (water-loving) and hydrophobic (water-hating) molecule groups. These compounds can be grouped by the charge of hydrophilic molecules, with distinct traits and uses for each type.

Surfactants are valued for their impact on the effectiveness of many types of products. However, they may also pose a danger to humans, animals, and water in high amounts, so care should be taken with their use and disposal.