What the Ingredients on Your Shampoo Bottle Actually Mean

By Andrew Tarantola on at

That shampoo you're lathering into your hair may claim that it's packed with "all-natural ingredients," but the label tells a different story. DMDM hydantoin? Ammonium lauryl sulphate? What is this stuff anyhow?

A History of Head Cleaners

Shampoos didn't always contain more unpronounceable ingredients than a Dow Chemicals storage locker. Some of the earliest known examples from Indonesia were made from alkali-rich rice straw ash mixed with water and lathered into the hair. This was followed by an application of coconut oil as conditioner to replace some of the stripped oils.

The practice also has its origins in the Indian subcontinent, where various herbal extracts like the nut of the Sapindus (a tree of the Lychee family) and gooseberries would be boiled and strained to form a liquid surfactant. In fact, the word shampoo is a derivative of the Hindi word "chāmpo."Both shampoo as a product and daily hygiene as a concept spread to Europe during the early colonial era. Those days, people would boil shaved soap in water with herbs (for fragrance) to create a liquid soap.

What the Ingredients On Your Shampoo Bottle Actually Mean

Soapnuts - Image: Dchauy

German inventor Hans Schwarzkopf is credited with inventing modern liquid shampoos in Berlin in 1927, but well into the 1930s folks in America were still using bar soap and water to clean their hair. Then, Proctor and Gamble got into the hair care business in a big way. The company formulated and produced Drene shampoo, the first modern synthetic shampoo (in that it used synthetic surfactants instead of soap). Aggressive marketing campaigns and a radio variety show sponsorship helped launch the Drene brand as a household name. P&G continued to sell Drene until the 1970s, when the company switched gears and began selling the equally-revolutionary 2-in-1 shampoo/conditioner combo, Head and Shoulders.

What's in Modern Shampoo

Americans buy more than a £633 million worth of shampoo each year—just a fraction of the £25 billion global annual hair care market. With that much money in the mix, shampoo manufacturers have taken increasingly extravagant marketing steps to differentiate their products from the competition. But no matter how exotic the botanical extracts that go into it are, almost all shampoos are concocted from the same basic ingredients:

Water: As much as 80 per cent of shampoo by volume is water.

Detergent: Shampoo's actual cleaning power comes from chemicals known as surfactants; often synthetics like ammonium lauryl sulphate or ammonium laureth sulphate. These chemicals make up about 10 to 15 per cent of shampoo and readily bind to both water and hydrophobic molecules. The act of lathering first binds these cleaning agents to the grease, oils, and grime on your hair, then also binds with passing water molecules to carry the grease away with the rinse water.

Shampoo, at its most basic level, can be made from the two ingredients above. But in this day and age, nobody'd buy the stuff—it's basically just soapy water. So, to transform shampoo into a more desirable product, manufacturers have steadily added ingredients from one or more of the following classes and augmented them with celebrity endorsements.

Foam Boosters: Having a shampoo that simply cleans your hair, no matter how effectively, simply isn't enough for the discerning modern consumer—they have to see it working. That means suds. Lots and lots of suds. So, to ensure that their products foam up into tufted bubbly peaks, shampoo makers utilize chemicals called alkanolamides. The two most commonly used types, lauramide DEA and cocamide DEA, are derived from fatty acids and often work in tandem with Triethylene Glycol, which maintains the foam's firmness by increasing the water's surface tension and preventing the bubbles from bursting prematurely.

Conditioning Agents: Once the detergents strip all the grease, dirt, and natural oils off of your hair, it's up to the shampoo's conditioning agent to moisturise the area, prevent frizz, and make the hair shine. Silicon-based oils like dimethicone (also found in Silly Putty) and cyclomethicone—as well as long chain fatty alcohols like cetyl or oleyl alcohol—are often used to make hair sleek and less prone to knotting. What's more, these fatty alcohols conduct electricity (if only very slightly) which helps eliminate static electricity and resulting hair frizz. Either panthenol or citric acid can be added to flatten hair follicles and increase your mane's shine.

Thickeners: The tactile aspects of shampoo are just as important to consumers as its effectiveness, perhaps even more so. Nobody wants watery shampoo, nor do they want to pump it out of the bottle like molasses. That's why table salt (no, really, it's sodium chloride) or ammonium chloride may be added to modulate the thickness of the mixture. Salt has a tendency to sting like the dickens when it gets in the eyes, so more expensive shampoo brands will often supplement other, more expensive thickeners along with the sodium chloride. These can include glycol distearate, cetyl alcohol, ammonium xylene sulfonate, and a host of others.

Preservatives: To stabilise the product and ensure that it doesn't break out in fungal, yeast, or bacterial colonies during its stay in your steamy shower, manufacturers add stuff like DMDM hydantoin and methylparaben. These potent antibiotics slowly release minute amounts of formaldehyde into the shampoo to kill off any potential protozoic invaders. Alternately, shampoo makers may instead opt for isothiazolinone or sodium benzoate.

Modifiers: It's not just whether the shampoo feels good in the hand—it has to be easy on the eyes as well. To that end, manufacturers will add a variety of dyes, waxes, and reflective particulate so the shampoo sparkles. Glycol distearate, for example, is added to make the mixture more opaque and reflective.

The shampoo's scent is also vitally important, not only informing the consumer that the product worked but also helping develop brand loyalty through a strong psychological connection to the product. That is, the stronger the connection, the more likely the consumer is to buy the product again. You can actually see this across a litany of consumer products such as the distinct smell of Irish Spring soap, Coca-cola's patented taste, or the unmistakable ruby glow of Mountain Dew: Code Red.

How They're Regulated

Like other cosmetics, regulatory jurisdiction of shampoo in the US falls to the Food and Drug Administration. The FDA defines cosmetics by their intended use, as "articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body...for cleansing, beautifying, promoting attractiveness, or altering the appearance." Interestingly, that doesn't apply to anti-dandruff shampoos. Since dandruff is considered a medical issue over in the US, shampoos containing anti-dandruff compounds are instead classified as drugs and are subject to a more strict set of regulations.

The FDA not only dictates what can and cannot go into a bottle of shampoo or onto the label, it also holds sway over the sorts of claims manufacturers can make. So if, for example, a shampoo claims to prevent sun damage or reduce dandruff, the FDA will require the the makers show that it does, in fact, block UV radiation or moisturise the scalp. Interestingly, competition between shampoo brands is a big factor in the industry's enforcement—as companies call out their competitors' claims against their own, they provide the FDA with ammunition to investigate both sides.

Unfortunately, the actual testing procedure to validate these claims is practically non-existent. According to the FDA website:

Companies and individuals who manufacture or market cosmetics have a legal responsibility to ensure the safety of their products. Neither the law nor FDA regulations require specific tests to demonstrate the safety of individual products or ingredients. The law also does not require cosmetic companies to share their safety information with FDA.

FDA has consistently advised manufacturers to use whatever testing is necessary to ensure the safety of their products and ingredients. Firms may substantiate safety in a number of ways. FDA has stated that "the safety of a product can be adequately substantiated through (a) reliance on already available toxicological test data on individual ingredients and on product formulations that are similar in composition to the particular cosmetic, and (b) performance of any additional toxicological and other tests that are appropriate in light of such existing data and information." (Federal Register, March 3, 1975, page 8916).

That's not to say the FDA is toothless, mind you. There are plenty of ingredients the agency has banned from cosmetics over the years. For example, the FDA nixed the synthetic dye Red #3, which was once commonly found in shampoo, in the 1970s—after rat research suggested it may be carcinogenic.

The future of shampoos, and the cosmetics industry in general, appears to be more of the same. Consumers will continue to drive demand for new and innovative hair care products, both influencing and being influenced by what manufacturers produce. Consumer demand should also spur the industry continuing develop cleaner, gentler, and more environmentally-friendly products. And if that doesn't work, there's always the ban hammer. [Wiki - Salon - P&G - Made How - Sci-Toys - Chemists Corner - Smithsonian Institute - Cosmetics Info - FDA - EFCR - Forbes]

lead image: Piotr Marcinski