Tell me what essential oil to use.
Creating products, Expert advice

Why are cosmetically active ingredients with antimicrobial activity important in skin care?

Melani 1 year ago 0

Dear readers, today I have the great honor to introduce another colleague and a dear friend of mine Prof. Dr. Nina Kočevar Glavač. We have collaborated together in various projects over the last decade the newest her being an exclusive guest to our Power Drops online education program.

At the Faculty of Pharmacy, Nina gives lectures in the area of medicinal plants, including topics such as pharmacognosy and cosmetic ingredients of natural origin, as well as aromatherapy and apitherapy as forms of alternative medicine. She also educates members of different professional associations, herbal associations and the general public about the therapeutic and safe use of medicinal plants, and cosmetic formulators about cosmetic ingredients in natural cosmetics.

Her research work involves the development of phytochemical methods for the analysis of natural compounds, e.g. capillary electrophoresis, high-performance liquid chromatography and antioxidative tests. In recent years, the focus of her research has been the study of vegetable butters and oils as therapeutically and cosmetically active ingredients.

Nina has written numerous scientific, professional and popular publications, with her main achievement in this area being ‘Modern Cosmetics, Ingredients of Natural Origin, A Scientific View’. This book is one of the most comprehensive publications of natural cosmetic ingredients in world, and has received the highest Slovenian award for scientific communication.

In terms of content, Modern Cosmetics is something entirely new in the field of scientific and popular literature. There is currently no such comprehensive description of cosmetic ingredients of natural origin and natural cosmetics anywhere in the world.

Nina is the editor-in-chief of the Pharmaceutical Journal of Slovenia and today she has shared this blog post with you. So, read below for her words of wisdom.


Dear enthusiasts of natural cosmetics and essential oils,
A warm welcome and a huge thanks for your commitment and curiosity.

As a scientist and a lecturer, I am very aware that education is of great importance for the quality of our professional and everyday life. Information is found literally everywhere today, but not everyone is capable of recognising reliable information. I am therefore very proud to see that you took the challenge to join us in the ‘EOs with the Pros & Modern CosmEthics’ course.

I will do my best to keep you engaged and interested when sharing my knowledge and views on natural cosmetics, as we journey through the pages of the Modern Cosmetics book.

Why are cosmetically active ingredients with antimicrobial activity important in skin care?

Many of you will be surprised to read about diverse aspects of antimicrobials as cosmetically active ingredients. They have an essential, yet provocative connotation. This may sound a bit strange, but here’s a typical example: preservatives. They are considered almost forbidden ingredients for many cosmetic DIYers and a thorn in the side of many manufacturers, but in terms of safety and regulations, they are generally an obligatory part of a cosmetic product alone. I will now encourage you to ponder a question: Are microbes evil or good or maybe even both for our skin?

Cosmetic products are usually not sterile, as in most cases there is no need for sterility. Food is not sterile, and even oral medicines are not sterile. In fact, our skin and mucosa are not sterile, as they are populated with different bacteria and fungi that enable the proper functioning of skin and mucosa. Cosmetic products must, however, meet legislative criteria regarding the requisite microbiological quality. This means that the quantity of all present microorganisms is limited. It is especially important that a cosmetic product does not contain pathogenic microorganisms.

An excessively high content of microorganisms spoils a cosmetic product and, even more important, it represents a health threat to consumers. The composition of a cosmetic product changes due to the presence of the metabolic products of microorganisms. This may result in the altered effects of a cosmetic product, and it may even cause an infection in a consumer. The risk of infection is especially relevant when talking about cosmetic products intended for use around the eyes, on mucosa and on injured skin, and for use in children up to three years of age, the elderly and patients with a compromised immune system. Microbiological quality criteria are stricter for such products.

The microbiological contamination of cosmetic products typically occurs in two ways: during manufacture and during use. In the first case, it is of the utmost importance to ensure proper conditions in the manufacture of cosmetic products and in the home-making of cosmetics. Preservatives should by no means serve as a substitute for good manufacturing practices. Quality must be incorporated into a cosmetic product.

Preservatives are used to maintain the adequate microbiological quality of cosmetic products. Their function is to prevent the reproduction of microorganisms that are initially present in a cosmetic product, and the reproduction of microorganisms that enter a cosmetic product during its use. Preservatives therefore have an antimicrobial effect.

Preservatives may also express side effects. These are usually limited to local reactions, e.g. skin irritation or even contact dermatitis. Systemic absorption may occur in very rare cases, which in turn may lead to disorders of the endocrine system, or even more rarely, serious damage to the liver or cancer. For this reason, the activity and safety of preservatives, as well as cosmetic ingredients in general, must be well documented. Last but not least, a poorly preserved cosmetic product also represents a health risk.

Synthetic compounds usually have a stronger antimicrobial activity than natural compounds. However, the skin usually better responds to natural compounds, as they are more likely to be metabolised or even reused as building blocks of the skin’s own biological molecules or structures. This also means they typically have fewer side effects. On the other hand, semi-synthetic derivatives may be considered a useful compromise in terms of the naturalness, as they are obtained from natural compounds. They may possess better efficacy, safety and stability properties.

Cosmetically active ingredients with an antimicrobial activity are not used solely for preservation. Microorganisms also play an important role in the formation of acne. It is a common disease that typically affects the skin on the face, neck, chest or back, usually of adolescents between 12 and 24 years of age, and is a result of the inflammation of the sebaceous glands. The increased incidence of acne during adolescence is due to increased hormone levels, which stimulate sebaceous glands to produce excessive amount of sebum. Other common causes of acne are hormone imbalance, bacterial skin infections, stress, an unhealthy diet and the use of unsuitable cosmetic products. The main microorganisms that cause acne are Propionibacterium acnes and Propionibacterium granulosum. Bacteria excrete lipases that degrade sebum triglycerides into free fatty acids. The latter may act pro-inflammatory and promote the formation of acne. Bacteria also excrete substances that attract leukocytes, which destroy hair follicles. Together with accumulated dead cells of the stratum corneum, the aforementioned factors lead to the clogging of sebaceous gland ducts, and finally blackheads form. However, acne develops when the infection and subsequent inflammation of blackheads occurs. Given how acne forms, it makes sense to use cosmetically active ingredients with an antimicrobial activity in the care of acne-prone skin and in the treatment of acne in dermatology.



  • Kokalj Ladan M. (2018) ‘Skin – the two most important square meters in our life’, in Kočevar Glavač N. and Janeš D. (eds.) Modern Cosmetics. Velenje: Širimo dobro besedo, pp. 22-46.
  • Kočevar Glavač N. (2018) ‘Vegetable butters and oils’, in Kočevar Glavač N. and Janeš D. (eds.) Modern Cosmetics. Velenje: Širimo dobro besedo, pp. 47-170.

Drop your Comment

Stay with us

Subscribe to receive our content in your inbox for FREE

The information you provide on this form will only be used to provide you with Dropsmith's updates and special offers for personalized marketing. Your privacy is important for us!

Please, wait until we subscribe you to our mailing list

Now, please check your email to confirm your subscription. Thank you.