The practice of sharing cosmetics, while common, carries a notable risk because makeup products can act as fomites, objects capable of carrying infectious organisms. These items, designed for personal application, can transfer bacteria, viruses, and fungi from one person to another. The risk of infection is highest when products are applied to areas with mucous membranes, such as the eyes and lips, or to skin that is already broken or irritated.
How Pathogens Transfer Through Shared Cosmetics
Pathogens are typically introduced into cosmetics through direct contact with natural secretions like saliva, tears, or the skin’s native microflora during application. Once inside the product, the formulation often provides a hospitable environment for microbial growth. Liquid and cream-based products, with their moisture and organic compounds, are particularly vulnerable to becoming breeding grounds for microorganisms.
The greatest risk comes from applicators repeatedly dipped back into the product container after touching the body. Mascara wands and lip gloss applicators, for instance, are dragged across the eye or lip surface and then reinserted into the tube, facilitating the transfer and incubation of bacteria. Similarly, liquid eyeliner brushes and lipstick bullets pick up surface microbes and deposit them deep into the product matrix. Shared retail testers pose a significant danger as they are used by numerous individuals who introduce a wide variety of microorganisms.
Bacterial and Viral Infections of the Eye and Skin
Shared cosmetics can transmit a range of infectious agents that target both the delicate tissues of the eye and the surface of the skin. The eyes are highly susceptible to infection, with conjunctivitis, commonly known as pink eye, being one of the most frequently transmitted conditions via shared eye makeup. Other bacterial infections, such as styes or blepharitis, can also result from using contaminated mascara or eyeliner, as bacteria colonize the lash line and eyelid margin.
Several species of bacteria from the genus Staphylococcus, including Staphylococcus aureus, are commonly found in contaminated makeup and are responsible for serious skin and eye infections. These bacteria can cause folliculitis, an inflammation of the hair follicles, or lead to more severe skin infections, particularly if the makeup is applied over blemishes or small cuts. Other microbes, like Pseudomonas aeruginosa and Escherichia coli, are also frequently isolated from shared cosmetic products and can cause rashes and abscesses.
Sharing lip products is a primary pathway for the transmission of viral infections, most notably Herpes Simplex Virus Type 1 (HSV-1), which causes cold sores. The virus can be transmitted even when the infected person shows no visible signs of an active sore, as it can be shed asymptomatically. Once contracted, HSV-1 is a lifelong infection, highlighting the risk of sharing lipsticks or lip balms. While less common, the transfer of common cold and flu viruses is also possible if makeup is shared immediately after touching the face, nose, or mouth.
Preventing Contamination and Spread
The most effective way to prevent the spread of pathogens is to establish a strict rule against sharing personal-use cosmetics, especially those applied to the lips or eyes. Products like mascara, liquid eyeliner, and lip gloss should be considered single-user items to avoid cross-contamination. Even when used personally, liquid eye products should be discarded approximately three months after opening, as their preservatives degrade and the risk of bacterial growth increases.
Maintaining the cleanliness of application tools is also important. Makeup brushes and sponges should be washed regularly with soap and water, allowing them to dry completely before the next use. When using retail cosmetic testers, avoid direct application to sensitive areas like the eyes and mouth; instead, swatch colors on the back of the hand or wrist. If testing is necessary, use only disposable, single-use applicators provided by the store.