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Oxidative stress is a widespread term in cosmetics given its association with detrimental effects on the skin.

In this article we’re going to take you through the whys and wherefores of oxidative stress. You’ll find out where it comes from and how it works. You’ll also see that it isn’t necessarily bad, as long as it’s kept under control. We’ll also be taking a look at the external factors that can aggravate oxidative stress and the molecules that can combat it.

Oxidative stress starts with respiration

Oxygen is a chemical element that is vital to virtually every living thing on the planet — humans, animals, plants, and even bacteria. It is generally associated with respiration, which is a series of biological reactions that enable the body to produce the energy it needs to function.

In humans, pulmonary ventilation (breathing) is only the visible part of this process. Most of the process of energy production takes place within cells, in microscopic organelles called mitochondria. This is called “cellular respiration”, a process in which the chemical energy found in the carbohydrates, fats, and proteins provided by the food we eat is converted. This energy is then used by the cell to keep it running.

Cellular respiration evolved as a process almost 2 billion years ago, when the Earth’s atmosphere became oxygen rich. Aerobic organisms (those that need oxygen to live) evolved in response to these new atmospheric conditions. They learned not only to consume and use oxygen, but also to eliminate the by-products of oxygen use, which is a crucial factor in dealing with oxidative stress.

These by-products, which you would probably know as free radicals, are what we’re going to talk about now.

So what are free radicals?

Free radicals, whose scientific acronym is ROS (Reactive Oxygen Species), were discovered in 1954 by American academic Denham Harman, the researcher behind the Free Radical Theory of Aging.

As mentioned above, they are by-products of cellular respiration. These extremely unstable chemical species are often toxic to cells. In order to stabilise themselves, they break down other cell constituents, which in turn causes the latter to become destabilised. Free radicals oxidise proteins, cell membranes, DNA, and more, causing the deterioration of the cell.

But it should be noted that free radicals aren’t automatically a bad thing. In much the same way as inflammation is necessary for healing or muscular regeneration after exercise, free radicals play an essential role in cell communication and the body’s overall state of balance.

In reality, it all depends on the amount of free radicals produced by the body.

Oxidative stress produces free radicals


Oxidative stress: when free radicals overwhelm the body

As breathing is essential to life, free radical production is inevitable. Thankfully, the body has its own way of neutralising them: it produces antioxidants that fight the oxidation of cell constituents.

When free radicals are produced in manageable quantities, their levels within cells remain stable — production and elimination of free radicals by antioxidants in the body are in balance.

But it’s a delicate balance that can be thrown off either by an excess of free radicals or by insufficient production of antioxidants. We call this imbalance oxidative stress.

Oxidative stress is sometimes only temporary. The body adapts by learning to produce extra antioxidants itself. This is an interesting and valuable process, as it helps to fortify the body against future imbalances or external stresses.

However, when oxidative stress persists, either because of a prolonged surge in the quantity of free radicals or because of an inadequate antioxidant response, considerable harm can be caused.

The causes and consequences of oxidative stress on the skin

Oxidative stress is one of the primary causes of skin ageing. Not only do we produce more free radicals as we age, but our skin’s ability to regenerate and protect itself using antioxidants also declines.

Furthermore, the various external factors that form the exposome can exacerbate the effects of oxidative stress.

The sun and UV radiation

Free radicals have been observed on the skin within the 15 minutes following exposure to UV radiation, with ROS quantities increasing for up to 60 minutes after exposure. When skin is exposed to too much and/or for too long, free radicals further degrade collagen and elastin, the proteins that give the skin its suppleness and tone, thereby accelerating skin ageing.

UV radiation is one of the primary causes of oxidative stress



Air pollution can significantly increase the oxidation of the skin’s surface. Airborne pollutants react with UV radiation to form ozone, which is well-known to city dwellers as the gas responsible for pollution warnings during the summer and heatwaves.

Although ozone cannot cross the skin barrier, it does cause oxidative stress by damaging the lipids present in the outermost layers of the skin.

Stress and tobacco

Chronic psychological stress has also been found to induce oxidative stress in the skin, while smoking reduces the natural production of antioxidants and the effectiveness of those provided by our diets (vitamin C especially).

This means that oxidative stress and free radicals are responsible for wrinkles, uneven skin texture, a dull complexion, and pigmentary abnormalities. To combat these unwelcome symptoms, aesthetic doctors recommend including antioxidants in skincare routines at the earliest possible opportunity.

If you would like to know more about vitamins C and E or niacinamide, our experts here at FILORGA have written an article just for our customers focusing on the beneficial effects of antioxidants.

Discover HYDRA-AOX, the antioxidant serum from Laboratoires FILORGA.

Migdal C, Serres M. Espèces réactives de l’oxygène et stress oxydant [Reactive oxygen species and oxidative stress]. Med Sci (Paris). 2011 Apr;27(4):405-12. French. doi: 10.1051/medsci/2011274017. Epub 2011 Apr 28. PMID: 21524406.