Above: Image © VectorPocket, iStockPhoto.com

Did you know that cosmetics have probably been used for over 6000 years? In ancient Egypt and China, both women and men used chemicals to darken their eyelids and paint their nails. Indigenous peoples all over the world have also been known to use crushed rocks and minerals to make body paint for ceremonies.

But what about the cosmetics you might see in your local drugstore? What is the chemistry behind modern makeup, and is it really safe to use?

What's in makeup?

Cosmetics are made up of many different components. One of the main ones is water. Many cosmetics are based on oil-in-water emulsions, small droplets of oil dispersed in water. Many others are based on water-in-oil emulsions, small droplets of water dispersed in oil. The cosmetics also contain an emulsifier (a substance that allows liquids to mix when they otherwise wouldn’t) which holds the water and oil together in a nice mix, stopping them from separating and forming layers.

Many cosmetics also contain alcohol, which works as a solvent. A solvent is something that carries or dissolves other ingredients. An nice example of solvent use in cosmetics is in nail varnish. The solvent carries a polymer with colour pigments, and after it evaporates off, you’re left with a nice film on your nails.

Other common substances in makeup include:

  • Preservatives, which prevent the growth of bacteria or microorganisms
  • Thickeners, which can give the product a nice texture and feeling
  • Emollients, which soften the skin by preventing it from losing water.

Makeup manufacturers then add colour, shine and a nice fragrance to give you a nice-looking and pleasant-smelling product!

Lipstick ingredients

Let’s now look specifically at lipstick, where two of the components are waxes and oils. Waxes and oils are compounds which contain mainly hydrogen and carbon. The wax is what gives the lipstick its structure and glossiness. There is a wide range of naturally-occurring waxes that chemists add to lipstick, such as beeswax, which mostly contains esters, organic acids and hydrocarbons.

Did you know? During the Second World War, food and many personal items were rationed. However, the British Prime Minister Winston Churchill kept lipstick production going. He said it boosted morale!

Chemists add various other ingredients to lipstick. For example, they add oils, such as olive oil, which soften the lip skin and add glossiness. Pigments and dyes provide the colours, and fragrances then cover up the nasty smell of the other chemicals. A common pigment in red lipstick is carmine red, which is derived from boiling an insect!

Above: Carmine red, a common pigment in red lipstick derived from scale insects.
Image © John Woodliffe

Some lipsticks even contain the compound capsaicin (the cause of spiciness in chili peppers) which irritates the skin and causes it to plump up!

Above: Capsaicin, the compound which gives chili peppers their spiciness!
Image © John Woodliffe

Jobs for the chemist

So we’ve seen how chemistry is used to make lipstick. However, the job doesn’t end there. Chemistry is also used to overcome certain issues so that these products will be effective - and popular!

One such issue is melting. Lipstick wouldn’t be much good if the solid waxes melted on your lips and ran down your chin! To solve this problem, chemists mix in some carnauba wax, which has a high melting point of around 87°C.

Is lipstick safe!?

Now that you know about all the chemicals in lipstick, you may ask if it’s really safe to put lipstick on your face, especially so close to your mouth! This has been the subject of some debate, with discussion in the media and online about the presence of potentially dangerous metals in lipstick and other cosmetics. For instance, one study found small amounts of metals such as chromium, manganese and lead in lip products. These metals can cause neurological problems, affect the nervous system or cause cancer. The question is, are the amounts of these metals found in lipstick high enough to cause problems? After all, we also have trace amounts of metals in our water and air!

Overall, I think that the regular use of lipstick is indeed safe. That’s because these products have been extensively tested before they can be used. Some of the chemicals may be dangerous in larger quantities, but in the tiny amounts used in cosmetics they’re most likely harmless. For instance, for the majority of the metals tested in the previously mentioned study, the researchers concluded that when people used those lip products daily, they absorbed safe levels of those metals. But the study did find that people who used these products daily absorbed enough chromium to have a noticeable impact on their health.

So in conclusion, we’ve seen that cosmetics have been used for thousands of years and that current cosmetics are based around a set of common ingredients or chemicals. We looked in more detail at the specific ingredients and chemistry of lipstick, and found that although some of their ingredients can be intimidating, scientists and regulators make sure that they are safe to use.

Learn more!

The chemistry of cosmetics (2017)
Australian academy of science

Concentrations and Potential Health Risks of Metals in Lip Products (2013)
Liu, S.K. Hammond & A. Rojas-Cheatham, Environmental Health Perspectives 121

What’s that stuff? Lipstick (1999)
Johnson, Chemical & Engineering News 77

Vegetable oils, emulsions and hydrogenation

John Woodliffe

John Woodliffe

My scientific studies really began when I attended the University of Cambridge, United Kingdom, studying natural sciences. After completing my bachelor’s degree, I went on to do a master’s degree in chemistry, staying on at Cambridge. Having graduated, I then worked for a year at a small R&D pharmaceutical company, developing and testing new drug formulations. Following that I got married to my lovely wife, Jess, and together we moved to South Korea as a sort of gap year, teaching English. Now nearing the end of that year we will soon return to the UK and I shall hopefully continue my studies with a PhD in inorganic chemistry. My hobbies include racket sports, playing the guitar and attending church!

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