A review of the use of beeswax in skincare

Beeswax is a naturally occurring product secreted from worker bees that has varied uses in modern day. In skincare, its function ranges from its role as an occlusive, helping to create a semi‐occlusive skin barrier that minimizes transepidermal water loss; as a humectant, locking in hydration; and an emollient to soften and soothe the skin. As a natural substance, its use has been shown to help alleviate symptoms associated with common cutaneous conditions like dermatitis, psoriasis, and overgrowth of normal skin flora.

Processing of beeswax is commonly performed through gas chromatography and mass spectrometry techniques. Its dynamic chemical properties allow it to take form in a solid state at room temperature and a liquid form when heat is applied. Structurally, alkanes, alkenes, free fatty acids, monoesters, diesters, and hydroxymonoesters make this hydrophobic compound useful as an occlusive, emollient, and humectant in skin care products. Commonly mixed in beeswax is a component called propolis. Propolis is made up of phenolic acids, esters, flavonoids, and aromatic compounds. Beeswax containing high levels of propolis helps to provide antioxidant, 2,3 antimicrobial, 1,4 and anti-inflammatory 5,6 properties.
As the largest organ of the human body, the skin provides protection against a multitude of external environmental irritants. The outermost layer called the stratum corneum (SC) plays a vital role in skin barrier protection. Transepidermal water loss (TEWL) passively occurs through the SC and is an indicator of the skin barrier integrity. When the skin barrier is disrupted, various cutaneous disorders can be triggered, including atopic dermatitis (AD), xerosis cutis, and psoriasis. 7 Occlusives like beeswax found in many skincare products can help to buffer excess TEWL. Other uses of beeswax in skincare that have been described in the literature include treatment of burns, ulcers, and wounds. This article aims to describe a collection of scientific articles characterizing uses of beeswax in skincare.

| ME THODS
A PubMed search for articles with the following keywords was performed: "beeswax" AND "skin" OR "dermatology" OR "dermis" OR "dermal." One-hundred and nine (109) articles resulted, and article titles and abstracts were reviewed. Those with relevant subject matter were retrieved for full-text review. In addition, their associated references were scanned for additional relevant reports.

| Effects on the microbiome
The antimicrobial properties of beeswax have been acknowledged since ancient times, depicted by its incorporation in ancient European and Asian traditional medicines. 8 Although there are few studies directly analyzing the antimicrobial efficacy of beeswax, two studies evaluated such activity against various bacterial strains.
Utilizing measurements including the zone of inhibition and minimum inhibitory concentration, Ghanem (2011) analyzed the effect of crude beeswax on both gram-positive and negative bacteria. 9 Although bee propolis was shown to have greater antimicrobial effects, crude beeswax is easier to obtain and still depicted efficacy against studied bacteria.  However, assessment of growth with separate media of (1) honey, (2) olive oil, and (3) beeswax revealed that the beeswax media was the least efficacious in preventing the growth of both S. aureus and C. albicans. Whereas the honey media completely inhibited growth, the olive oil media exhibited mild growth, and the beeswax media exhibited moderate growth. Yet, the control media consisting solely of nutrient agar depicted heavy growth, suggesting that beeswax still has intrinsic antimicrobial properties, albeit to a lesser extent than the other two ingredients.

| Protecting the skin barrier
One of the many functions of the skin is to provide protection from external environmental irritants, such as sun irradiation and bacterial infections. The stratum corneum (SC) plays a key role in this skin barrier function by preventing transepidermal water loss (TEWL) that can be caused by environmental irritants. 7 Occlusives such as petrolatum and mineral oil coat the SC to inhibit TEWL.
Because petroleum in the form of crude oil has much greater shelf life and more protective effects on water vapor loss as compared to olive oil, it has become the gold standard of occlusives. Although effective, petroleum products have a greasy texture that many people dislike. Several additional occlusives including waxes (i.e., lanolin, paraffin, squalene, dimethicone, and propylene glycol) and natural oils (i.e., soybean, grapeseed, sunflower seed, evening primrose, olive, and jojoba oils) are commonly used as cosmetic ingredients.
Beeswax is similarly an effective occlusive, as it forms a film on the skin's surface and resultantly protects against many external irritants. 12 The literature search included two studies that evaluated the use of a beeswax-containing formulation on measures of skin barrier integrity. Healthy skin tends to have low TEWL and high stratum corneum water content (SCWC), whereas a damaged skin barrier is associated with increasing TEWL. 13 In 2003, Frosch et al. evaluated the efficacy of various barrier creams vs. skin care products in dental laboratory technicians. 14 Dental laboratory technicians commonly experience irritant contact dermatitis due to frequent contact with irritants, yet traditional barrier creams can reduce the required tight grip of tools and risk contamination. As such, the authors compared two commercial barrier creams with a moisturizer containing either urea or beeswax. Of those receiving the first commercial cream, 58% reported a "good" or "very good" response, compared to 67% with the second commercial cream. On the contrary, 77% with the urea-containing moisturizer and 98% with the beeswax-containing moisturizer reported a "good" or "very good" response. Furthermore, improvement of skin condition, including erythema, infiltration, vesicles, fissures, and scaling, was as follows: 35% (barrier cream 1), 44% (barrier cream 2), 55%

| Uses in dermatitis and psoriasis
A combination of skin barrier dysfunction and immune dysregulation has been elucidated in the pathogenesis of atopic dermatitis (AD). Therapies for AD have focused on restoring the skin barrier through increased skin moisture retention. A study by Park et al (2021) examined the effects of cera flava (CF), which is a natural extract from beehives that is modified through heath compression filtration and purification, on a mouse model of AD. 15 Using house dust mite as an irritant, the authors found that use of CF attenuated symptoms of pruritus and increased skin moisture content; restored skin barrier proteins like filaggrin, claudin-1, and occludin; and downregulated immune signaling associated with an inflammatory response.
A study by Al-Waili (2003) evaluated the effects of a product containing beeswax for AD and psoriasis. 16 Psoriasis is a chronic inflammatory state that triggers a rapid turnover of skin cells, leading to thickening of the outermost layer of the skin. The mixture included honey, olive oil, and beeswax in a 1:1:1 ratio, and was prepared in various proportions with a corticosteroid ointment (Mixture A was 1:1, Mixture B was 2:1, and Mixture C was 3:1). In those with AD, there was a significant improvement in signs and symptoms in 80% of patients who did not have prior treatment for the disease. Among those who were using a corticosteroid therapy

| Uses in burns
In addition to restoration and maintenance of the skin barrier, beeswax is thought to be particularly effective in the treatment of burns. Pharmaceutical use of beeswax to treat burns dates back to ancient Egypt, where beeswax was the primary ingredient in many ointments and creams. It has since been utilized extensively in ancient Rome and Ayurvedic medicine. 1 The literature search included five studies that evaluated the use of a beeswaxcontaining mixture in the treatment of burns, three of which involved animal models. However, as the mixtures contain other ingredients such as olive oil, honey, butter, and herbal oil, future studies that evaluate beeswax alone would be needed to assess its specific effect.
In 2015, Moustafa and Atiba evaluated the efficacy of a mixture of honey, beeswax, and olive oil (MHBO) in the treatment of seconddegree burns in canines. 18 Beeswax was included in the mixture due to its antibacterial properties. Three second-degree burns were produced in five canines, one of which was treated with the MHBO mixture, one of which was treated with silver sulfadiazine (SSD), and the remaining burn left untreated (control). The authors found wound contraction to be greater in the MHBO group, while the time for complete wound healing was significantly shorter. Furthermore, less exudation and inflammatory reaction were observed in the MHBO than in the SSD and control groups. It should be noted that honey has been observed to reduce pain, edema, exudates, and scar formation, while accelerating wound healing and inhibiting toxin production. 18 As such, the efficacy of beeswax alone was not assessed but only as part of a formulation.
In 2020, Ebrahimpour et al. similarly conducted an animal study evaluating the efficacy of a beeswax-containing substance on burns. 19 They assessed the wound closure rate and neovascularization of second-degree burn wounds in rats following the application of Lime Salve (LS), a mixture containing calcium hydroxide powder, beeswax, and sesame oil. In comparison with the control group receiving normal saline, they found that LS increased wound closure rate and neovascularization on Day 10, in addition to collagen formation on Days 17 and 24. Interestingly, they also included a treatment group composed solely of beeswax and sesame oil (B group). There were no differences in histological scores between the B group and those receiving LS (T group); however, on Day 24, reepithelialization was significantly increased in the T group compared to the B group (p < 0.001), and collagen in the T group was more distributed. Furthermore, on Day 17, the wound surface of the B group was more bruised compared to the T group. These results suggest that the mixture including calcium hydroxide powder was more efficacious than the mixture solely containing beeswax and sesame oil, although both were superior to normal saline.
In addition to assessing the effects of beeswax, olive oil, and butter (BOB) on second-degree burn wound healing in rats, Bayir The authors found that BOB treatment increased regeneration of the epidermis and dermis, increased keratinization and fibroblast activity, and exhibited greater wound contraction levels than the burn control group (no topical treatment). Furthermore, BOB treatment increased TGF-β1 and VEGFα expressions compared to the control group (p < 0.05), suggesting a mechanism for which the BOB treatment encouraged skin renewal and tissue modulation.
The utility of beeswax-containing substances has additionally been demonstrated in human subjects. Gümüş and Özlü (2017) conducted an experimental study to assess the effect of a mixture containing beeswax, olive oil, and Alkanna tinctoria Taush on epithelization initiation time, pain scores, and hospitalization duration. 21 31 second-degree burn victims received the treatment mixture, and 33 second-degree burn victims received the clinic's routine dressing (control). They found the treatment mixture to significantly reduce epithelization initiation time, mean pain scores, and hospitalization duration (p < 0.05). Furthermore, whereas infections occurred in 6.1% of control group wound cultures, no infections occurred in experimental group wound cultures, likely due to the antioxidant, antibacterial, and anti-inflammatory properties of A. tinctoria, beeswax, and olive oil. 21 The authors attributed the significantly reduced pain scores to A. tinctoria and olive oil, although they suggested that the beeswax contributed to reduced epithelization initiation time and mean hospital duration.
The prior studies have depicted beeswax-containing products to be efficacious in wound healing following second-degree burns, both in animal models and in human subjects. In addition, Lewis et al.
suggest an additional use for beeswax in burn victims: relief from postburn pruritus. 22 Postburn pruritus (itch) greatly impacts the burn population and has been reported to affect up to 87% of burn victims. The authors sought to assess the efficacy of beeswax and herbal oil cream against standard treatment (aqueous cream) in relief from postburn symptoms of pruritus. The results depict that the beeswax and herbal cream reduces itch more frequently than aqueous cream (p = 0.001) and prolongs recurrence of itch (p ≤ 0.001).
Taken together, the literature suggests that beeswax-containing mixtures can effectively contribute to greater wound contraction, neovascularization, keratinization, and fibroblast activity; reduced exudation and inflammation, epithelization initiation time, and mean pain scores; and provide relief from postburn pruritus. The results of each study are depicted in Table 1. Additional randomized, controlled trials are necessary to analyze the effects of beeswax alone so that efficacy measures are not confounded by other contained ingredients.

| Role in cosmetics
Beeswax is used extensively in the manufacture of cosmetics, primarily as a thickener used in occlusives. When combined with an ingredient such as borax, it acts as an emulsifier. To prepare it for cosmetic use, honey is removed from honeycombs, followed by melting of the wax and separation of impurities through solar, electric, or TA B L E 1 Summary of articles with beeswax-containing products for burn management can be used to alter a cosmetic product's physical properties, such as to increase a lipstick's luster and hardness, enhance its color and sensory characteristics, and improve its application characteristics.
For example, it is used as a stiffener to provide elasticity, plasticity, and increase skin adhesiveness. 12 Beeswax has been shown to be nonirritating and generally has a low comedogenic potential, 23 in addition to its previously noted antimicrobial, anti-inflammatory, and antioxidant properties.

| Allergies and noxious effects
Beeswax is not considered an irritant and does not have a high potential for causing blackheads through blockage of pores.
Furthermore, the literature suggests that contact allergy to beeswax is greatly uncommon relative to the extent of its usage. 24 Of the many products derived from bees, beeswax is the least allergenic. Reports of allergic reactions to beeswax-containing products appear to be attributable to contamination with other products such as propolis or resins. For example, a case of occupational dermatitis in a beekeeper was determined to result from poplar resins in the beeswax. 25 Furthermore, Borlin (1947) discussed several cases of allergic contact dermatitis from beeswax that depicted positive reactions to unpurified beeswax but negative reactions to purified beeswax. 26 Still, cases of occupational dermatitis 27 and contact cheilitis 28

TA B L E 1 (Continued)
Additional research is needed to better understand beeswax as used both independently and in combination with other skincare ingredients for the application of general skin barrier health and as a therapeutic modality. Future studies should aim to further assess the specific antimicrobial, anti-inflammatory, and antioxidant properties offered by beeswax and its components that enable it to be used in a multi-faceted manner.

ACK N OWLED G M ENTS
This article was supported by Burt's Bees©.

FU N D I N G I N FO R M ATI O N
Funding for this study was provided by Burt's Bees.

E TH I C A L A PPROVA L
This study did not require review by an Institutional Review Board as there is no involvement of human subjects.

DATA AVA I L A B I L I T Y S TAT E M E N T
Data sharing is not applicable to this article as no new data were created or analyzed in this study.