A Whiff of Trouble: Navigating Allergic Contact Dermatitis to Fragrance
Fragrances are found in abundance in everyday life—from obvious sources such as perfumes, colognes, and air fresheners, to not-so-common sources, such as workplace exposures. Problematically, even products labeled as “fragrance free” may contain covert fragrances. Patients and physicians alike should be aware that fragrances are a common cause of allergic contact dermatitis (ACD) and that patient education is critical to treatment success. In this review, we discuss the chemistry and epidemiology of fragrance ACD, patch test considerations, skillful patient education on avoidance, and potential pitfalls for patients with fragrance allergy—all to empower treating clinicians with the knowledge to effectively address patient needs.
Practice Points
- Fragrance allergy is common due to daily exposure from many sources, ranging from personal care products and cosmetics to cleaning products, foods/spices, and workplace materials.
- More than 100 different fragrances can cause contact allergy, but patch testing in routine practice usually is limited to a few key screening allergens with important limitations.
- Fragrance avoidance is challenging, and comprehensive patient education is critical, including the provision of a list of safe products that are truly fragrance free.
Avoiding Fragrances: Improving Patient Education and Outcomes
Once a relevant contact allergy to fragrance is established after patch testing, successful avoidance is critical but challenging, as there are numerous potential pitfalls. Missing just 1 hidden source of fragrance exposure will often be the difference between success or failure. Dermatologists play a crucial role in guiding patients through the intricate process of identifying and avoiding potential allergens.
Optimal Safety: Embracing a Fragrance-Free Lifestyle
For fragrance-allergic patients, it generally is safest to completely avoid fragrance.
First, if a patient only shows positive patch-test reactions to fragrance screening mixes (and not to the particular fragrances in these mixes), there is no way to be certain which fragrances the patient needs to avoid.
Second, even if specific fragrance allergens are identified, numerous chemically related fragrances to which the patient may be allergic are not commercially available for patch testing. One review provided evidence of 162 fragrance allergens that have been documented to cause contact allergy.1 Dermatologists generally patch test to screening mixtures and/or the 26 fragrance chemicals required on labels in European products (European Directive fragrance).27 Therefore, there are more than 100 known fragrance allergens that are not routinely tested to which patients could be allergic.
Third, certain fragrances, such as limonene and linalool, are found in many products with fragrance, and it is difficult to find products without these substances. Limonene and linalool themselves are not potent allergens; however, upon air exposure, they may auto-oxidize to hydroperoxides of limonene and linalool, which are increasingly common positive patch tests.19
Additionally, patients should be advised that many products labeled “fragrance free,” “unscented,” or “free and clear” are not truly fragrance free, and patients should not choose products based on these claims. There are no legal definitions for these claims in the United States, and industries are allowed to choose the definition they prefer. Numerous products labeled “unscented” use this term to indicate that the product had an odor, the company used a masking fragrance to hide the odor, and then the product can be considered unscented. In many holistic stores, most products labeled “fragrance free” are only free of artificial fragrances but contain essential oils. Of the 162 documented fragrance allergens, 80 are essential oils.6 Essential oils are perceived to be safe by the vast majority of the population because they are viewed as “natural” and “unprocessed” sources of fragrance.28 However, numerous allergenic terpenes have been discovered in essential oils, including functionalized variations of alcohols (eg, geraniol, bisabolol) and aldehydes (eg, citronellal).6 Essential oils also consist of nonterpenic compounds produced through the phenylpropanoids pathway, including eugenol and cinnamaldehyde. One review showed that most essential oils contain one or more European Directive fragrance.29 Therefore, many products labeled “unscented,” “fragrance free,” or “natural” are not free of fragrance and may be unsafe for fragrance-allergic patients.
Although not required, manufacturers sometimes voluntarily list one or more of the 162 currently identified fragrance allergens on product labels. Also, there are more than 50 potentially allergenic essential oils that can be listed on labels by their common names or by genus or species. In addition, there are synonyms for fragrance, such as aroma, parfum, perfume, and scent. Therefore, there are several hundred different ingredient names on labels that indicate the presence of fragrance, and patients are very unlikely to successfully identify fragrance-free products by trying to read product labels on their own.
Lastly, in the United States product labels only require products to state that they contain “fragrance” and do not mandate the listing of specific fragrances. If a patient is allergic to a specific fragrance, there is no way to determine if that fragrance is present in these products. This will change with the enactment of Modernization of Cosmetics Regulation Act of 2022, which empowers the US Food and Drug Administration to require manufacturers to disclose many, but not all, fragrance allergens on the labels of cosmetic and topical products.26
For all these reasons, patients should be advised to use a medical database to choose safe alternative products instead of trying to read labels themselves to avoid fragrance. The American Contact Dermatitis Society’s Contact Allergen Management Program (CAMP) database (https://www.contactderm.org/resources/acds-camp) is designed to identify safe alternative products for patients with contact allergies. When CAMP is programmed to avoid “fragrance,” it will list only “safe” products free of all fragrances found in a comprehensive fragrance cross-reactor group.30 This customizable database is available as an application that can be downloaded onto a patient’s mobile device. Fragrance-allergic patients should be encouraged to use the CAMP application or other similar applications (eg, SkinSAFE)(https://www.skinsafeproducts.com/) to find all the products they use.
