Are all skincare preservatives bad? No, some are essential, but you need to know which are good and which to avoid

Preservatives are ingredients – either natural or synthetic – added to give a product durability. They prevent the growth of yeast, mould and bacteria, and address chemical imbalances that could jeopardise a formula’s efficacy and strength.

Without them the active ingredients in your formulas will start deteriorating and bacteria can thrive, making the products ineffective and increasing the possibility of irritation and infections.

Preservatives are also essential to keeping formulas fresh and functional. However, it’s important to understand that not all preservatives work in the same way – and that while some should be avoided, others are completely safe.

Protective packaging and optimising of ingredients are necessary to keep foods safe for human consumption – and to meet skin-safety requirements, key when manufacturing beauty products.

Since water is generally one of the main ingredients in skincare products, the risk of bacterial growth is high, given that many microorganisms spread and reproduce quickly in watery environments. Preservatives destroy parasites and build a safe environment where it’s difficult for bacteria to proliferate.

Are they safe for your skin?

Preservatives keep your products stable, but several have been proven to be a threat to human health, and should be avoided.

In the past few decades, preservatives have earned a rather bad reputation, which has led to a wave of products being marketed as “preservative-free”. However, these can harm your skin if not made properly.

“Many so-called natural brands are beginning to do this, which has become a big problem,” says Tara Foley, CEO of natural-beauty store Follain. “Preservatives are not all bad, and they need to be listed – along with everything else – so consumers can know what they’re feeding their skin.”

As a general rule, if a skincare product features water on its ingredient list, then preservatives are necessary. The only products that may be safely developed without them are anhydrous formulas – products made of oils, butter and waxes and without water.

A list of skincare ingredients often considered harmful, including preservatives.

Different kinds of preservatives

The key to understanding preservatives is being aware of the differences between the good and bad ones. There are natural and synthetic preservatives, and in both categories you’ll find a few that may be damaging to the skin and even toxic in some cases.

The bad ones: as a general rule, parabens should be avoided. Some of them, such as butylparaben, isopropyl paraben, and propylparaben, have been rated toxic by The Good Face Project – a formulation, regulatory, and innovation platform used by cosmetic developers to build safe, compliant and effective beauty products.

Chemical preservatives can be bad in high doses, but the quantities used in cosmetics are usually minimal

Bella Schneider, aesthetic scientist and product formulator

These preservatives have the capacity to disrupt our endocrine system, leading to health issues and, in some cases, cancer.

Another common preservative to stay away from is formaldehyde, which is used to extend shelf life and prevent bacterial growth; it can cause side effects such as irritation, rashes, skin burns, hair loss and cancer.

Some brands get away with using it without its name appearing in the ingredients list by using formaldehyde releasers, a form of chemical that releases formaldehyde molecules as it decomposes.

So instead of formaldehyde, you’ll usually see listed things such as DMDM hydantoin, quaternium-15, methylene glycol, glyoxal and imidazolidinyl urea – most commonly found in hair-straightening treatments, eyelash glue, nail polish, polish remover, shampoo and body wash.

Other names to keep in mind are isothiazolinone, methylisothiazolinone, benzyl benzoate, benzalkonium chloride and methyleugenol, which, according to clinical studies, can cause anything from contact dermatitis to irritation, urticaria, oedema, system toxicity, burns, occupational asthma and cancer.

Preservatives are used in small doses to prevent products from spoiling.

The good ones: Some preservatives are not just good, but necessary for our cosmetics to perform. One of the most commonly used is phenoxyethanol, a natural preservative – although it can also be made synthetically in labs – that’s safe for humans when used in concentrations of 1 per cent or less.

Other good preservatives are sodium benzoate, potassium sorbate, ethylhexylglycerin, and propylene glycol, which help kill microbes and stop the active ingredients in your formulas going off.

“Chemical preservatives can be bad in high doses, but the quantities used in cosmetics are usually minimal,” says Bella Schneider, an aesthetic scientist and product formulator. She points out how they work in small quantities and don’t have the heavy smells and textures that some natural preservatives do.

“They are inexpensive and efficient, prevent contamination, and make it possible for consumers to store their products outside the refrigerator for long periods of time,” she says.