The future of dandruff control

In the wake of European regulatory changes, Laura Meunier, Dr Florian Genrich and Dr Steffen Nordzieke of Symrise discuss how dandruff is formed and present suitable future-proof solutions to keep dandruff under control.

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Zinc pyrithione is one of the most frequently used ingredients in dandruff control. Its ban from the European cosmetic market is a hot topic, bringing drastic changes to the hair care industry.1 Manufacturers of anti-dandruff products around the world face are now faced with having to find suitable alternatives that meet changing regulatory requirements as well as growing consumer awareness.

Dandruff is a common scalp condition affecting more than a third of the global population. From as far as China to Germany and Brazil, from Gen Z to millennials to baby boomers and regardless of gender, dandruff is considerably affecting consumers’ confidence. Representative market reviews reveal that many people with dandruff are looking for natural solutions and for products that will leave the hair smooth and that are not irritating the scalp.2

Dandruff formation

There are different reasons why flakes can appear on the scalp. Not always easy to differentiate from dry scalp, dandruff typically is the result of an oily scalp leading to the overgrowth of Malassezia, a fungus feeding on sebum overproduction (figure 1).3 Malassezia is naturally part of the scalp microbiome of most healthy humans.4

Figure 1: The formation of dandruff

Until today, it is still not fully explored why some people develop dandruff and others do not. It seems that genetics play a role along with environmental factors like pollution, an intense cleansing routine, stress and cold weather. The first choice to treat dandruff symptoms is typically the use of anti-fungal actives. This is based on the conclusion that the healthy microbial equilibrium is disturbed on flaky scalp due to an overgrowth of certain microorganisms.

On the other hand, flaky scalp is not always linked to Malassezia and sebum overgrowth. In that case, formulations should focus on combining caring effects with anti-dandruff activity.

A traditional antimicrobial option

Antimicrobials remain the most popular solution to target dandruff. These ingredients control the overgrowth of microorganisms on scalp, more specifically the Malassezia genus which is linked to dandruff formation. Among these solutions, the most widely used and commonly known for their efficacy are:

  • climbazole (Crinipan® AD)
  • zinc pyrithione (ZPT)
  • piroctone olamine (PO).

The regulatory change that prohibits the use of ZPT in the EU has been effective since 1 March 2022. This change is also expected to affect the global market in the coming years as the number of products launched with zinc pyrithione has decreased over the past three years (figure 2).

Figure 2: The consequences of the new regulation for zinc pyrithione on various regions within the global market
Source: Mintel5

According to current European law, climbazole may be used in rinse-off anti-dandruff shampoos up to 2% (Annex III/310), though it has lower use levels in other applications (Annex V/32).6,7 These limits have been in place since 2019. In the past, a commonly accepted maximum use level of up to 0.5% across the whole range of cosmetics was common practice. This level is still valid today in some countries, like China.

Symrise has performed several in vivo studies, comparing the effectiveness of the three traditional anti-dandruff actives. One of these investigations compared the efficacy of 0.5% climbazole to 0.5% ZPT in an identical shampoo base. With both, dandruff score and hair greasiness were evaluated by six experts. Both parameters were evaluated on a scale of 1 to 6, with 1 being nothing and 6, extreme. This six-week evaluation was conducted on 30 subjects. Half the group used a shampoo containing climbazole and the other half a shampoo with ZPT. The conclusion of this study showed that climbazole significantly reduced dandruff within the period of 42 days of treatment, having a similar efficacy to ZPT as seen in figure 3. In addition, climbazole showed a stronger reduction of greasiness on scalp compared to ZPT, additionally helping to prevent new dandruff formation (see figures 1 and 3).

Globally compliant multifunctional

SymClariol® (decylene glycol) is used around the world as cosmetic ingredient to tackle multiple aspects of personal hygiene. The emollient’s lipophilic nature and antimicrobial profile make it an ideal multifunctional ingredient for cosmetic hygiene products from scalp care to foot care. For hair and scalp care applications its recommended use level is up to 2%. The performance of the molecule on the scalp in helping to reduce sebum as well as dandruff has been demonstrated in a study by Beauty Hi-tech Innovation.8 

A further study by Symrise, conducted on 13 subjects, confirms the efficacy of shampoos containing a reduced dosage (0.1%) of climbazole combined with 1% of SymClariol®. The subjects washed their hair three times per week with the test shampoo. After 42 days of use, the dandruff score decreased significantly, and the subjects stated that the shampoo helped in reducing scalp itching (figure 4).9

Figure 4: Shampoo study with 0.1% climbazole and 1% decylene glycol, from left to right: mean dandruff intensity; percentage of reduction of dandruff; percentage of the subjects’ statement that the test shampoos removed dandruff or reduced scalp itching

This data suggest that manufacturers can either combine decylene glycol with an established anti-dandruff like climbazole or even rely on SymClariol® alone. The combination of ingredients can be leveraged to boost the overall anti-dandruff efficacy of the hair care product. This was shown in a Beiersdorf study, where a combination of 0.5% climbazole and 0.5% piroctone olamine in a shampoo reduced dandruff more thoroughly than a shampoo with 1.0% zinc pyrithione alone.12  

Naturally derived easy-to-handle solution

Crinipan® PMC green (propanediol caprylate) was introduced in 2020 as a next generation anti-dandruff active from natural origin.13 This ester represents a new mode of action with a targeted release of an ingredient that prevents Malassezia from producing the fatty acids needed for its growth and to build its cell membrane. The yeast release lipases (enzymes) to cleave triglycerides contained in the scalp’s sebum into alcohol and fatty acids. Instead of the scalp sebum, Malassezia cleaves the ester into caprylic acid and propanediol (figure 5). While caprylic acid has direct anti-fungal properties, the application of the propanediol ester masks the strong smell of caprylic acid and brings other beneficial properties.

Crinipan® PMC green showed comparable efficacy to the benchmark climbazole, with a significant reduction of dandruff when used at 0.5%.14

To demonstrate the dandruff-reducing efficacy of propanediol caprylate in comparison to piroctone olamine, a shampoo study was conducted over a period of 28 days on 21 volunteers with greasy scalp. Non-adherent and adherent dandruff were evaluated by a dermatologist using a scale from 0 (no dandruff) to 5 (very large quantity of dandruff) on the entire scalp. The resulting total dandruff score (adherent and non-adherent) scales from 0 to 10. The shampoos contained either 0.5% propanediol caprylate or 0.5% piroctone olamine and were used three times a week. After 28 days, both shampoos showed a significant reduction of total dandruff flaking. There was no major difference between the two shampoos which clearly confirms the excellent efficacy of Crinipan® PMC green.

In addition to significantly reducing dandruff, further studies have shown that Crinipan® PMC green supports a healthier scalp microbiome and provides additional benefits like softer skin, shinier hair as well as ease of detangling and helping to reduce sebum.15

The recommended use level of Crinipan® PMC green is 1.0% in cosmetic applications. A great advantage of this material is that it is a liquid, which is easy to handle as it does not require a lot of energy during the production process of the cosmetic product. No heating or robust mixing are necessary to solubilise the material.

All-in-one liquid solution

The solid form of conventional antimicrobial ingredients like ZPT, PO or climbazole may present a challenge to some formulators. In most cases, to solubilise them into a formulation requires energy like heat or at least a prolonged stirring.

To overcome these challenges, formulators may opt to use Crinipan® ADS, a liquid blend that contains climbazole as well as phenoxyethanol, decylene glycol, and 1,2-hexanediol. In addition to limiting the overgrowth of Malassezia thanks to its anti-dandruff climbazole, this liquid all-round solution is successful in providing a complete preservation system when used at 1.5% in a shampoo formulation.16, 17.

Figure 5: Mode of action of Crinipan® PMC green

Conclusion

The zinc pyrithione ban has already hit the European market and is expected to affect the global market in years to come. There is a wide palette of alternative anti-dandruff solutions available to formulators – from the most traditional antimicrobial solutions like Crinipan® AD to ingredients that are easier to handle, such as Crinipan® ADS. These solutions are available from Symrise Cosmetic Ingredients.

Figure 6: Crinipan® PMC green performs equally to piroctone olamine; both shampoos showed a significant reduction of dandruff

Another option is Crinipan® PMC green, which represents the future of dandruff control. This natural derived and easy-to-handle solution supports a healthy scalp microbiome through an entirely novel and innovative mode of action.

Thanks to its China compliance, SymClariol® (decylene glycol) is an additional option particularly for applications targeting global markets. The combination of more than one technology remains a common practice to aim for an enhanced performance of the hair care formulation, providing multiple benefits.

*References available on request.

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Pharmaceutical & Cosmetic Review August 2023

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