Contact Dermatitis, Patch Testing, Cosmetics, Personal Care Products



  1. Aouthmany, Mouhammad
  2. Sheehan, Michael


ABSTRACT: This article discusses the testing of cosmetic and personal products for patch testing.


Article Content

Cosmetic and personal products are a broad category that includes any substance that may be applied to the body with intention to cleanse, beautify, or alter appearance. The prevalence of allergic reactions to cosmetics and personal products has been reported to be close to 10% among patients undergoing patch testing to standard and cosmetic series (Wetter et al., 2010). When evaluating a patient for possible allergic contact dermatitis, it can be helpful to request all personal care products to be brought to the office for review during patch testing. This can allow for augmented patch testing utilizing the patient's own products. Figure 1 illustrates a positive patch test using a patient's personal lip balm in the case of chronic lip dermatitis. Unknown substances or unlabeled products should not be tested. It should also be remembered that expanded patch testing, testing to cosmetic and personal products, and patch testing in patients under 18 years old is considered off label. Currently, the only system approved by the Food and Drug Administration for patch testing in the United States is the Thin-Layer Rapid Use Epicutaneous Patch Test or T.R.U.E. Test system of 35 standard patch test allergens, which is indicated in patients 18 years old and older suspected of having allergic contact dermatitis.

Figure 1 - Click to enlarge in new windowFIGURE 1. Positive patch test to lip balm.

When testing cosmetics and personal products, the intent of use for the product will help guide testing. Products not intended for long-term skin contact such as washes or shampoos typically require dilution before testing. Prolonged skin contact under patch test occlusion for rinse-off products will often result in irritant reactions if dilution is not performed. This may be misinterpreted as a positive patch test. Conversely, products intended for prolonged skin contact such as moisturizers, balms, and makeup can typically be tested as they are without dilution.


To prepare a dilution series for testing, first, mix one drop of the test substance with nine drops of the diluent (mineral oil, sterile saline, or petrolatum). This will yield a dilution of 1:10 or 10% dilution, which means that, in 10 total parts, you have one part being your test substance. Taking one drop from your 1:10 dilution and adding nine drops of the diluent, you will have a 1:100 or 1% dilution. This same technique can be carried out to derive 0.1% and 0.01% dilutions if needed.



Initial patch testing should be performed as discussed in the section "Schedules for Application and Reading Patch Testing" with the additional recommendations:


Consider an open or semiopen test first for potentially irritating products such as washes and cleansers. As noted above, serial dilutions should be used for these products as concentrated products may result in strong irritant reactions such as ulceration or bullous reactions.


To perform an open test, the substance is applied to the upper arm twice a day for at least 2 days without occlusion.


To perform a semiopen test, a minute amount of the test substance is applied using a cotton tip applicator to the arm and spread over a 1-cm2 area. The substance is allowed to air dry before occlusion with acrylic tape. Readings are performed in standard fashion at 48 and 96 hours.


Consider a repeat open application test for leave-on cosmetics and personal products. To perform a repeat open application test, instruct the patient to apply a small amount of the test substance (approximately 0.1 ml) to the antecubital fossa twice a day for 1 week and observe for the development of dermatitis.


See Table 1 for further information on product testing. Note that some products may have more than one vehicle option (adapted from Groot, 2008).

Table 1 - Click to enlarge in new windowTABLE 1 Patch Testing Guidelines for Cosmetics and Personal Products



Standard patch testing may miss potential allergens that are in cosmetics and personal products. A more personalized approach to patch testing by using a patient's own products can increase diagnostic yield. Familiarity with recommended application and testing of cosmetic and personal products can help minimize erroneous results and adverse reactions.




Groot A. C. (2008). Patch testing: Test concentrations and vehicles for 4350 chemicals (3rd ed.). Wapserveen, Netherlands: Acdegroot Publishing. [Context Link]


Wetter D. A., Yiannias J. A., Prakash A. V., Davis M. D., Farmer S. A., el-Azhary R. A. (2010). Results of patch testing to personal care product allergens in a standard series and a supplemental cosmetic series: An analysis of 945 patients from the Mayo Clinic Contact Dermatitis Group, 2000-2007. Journal of the American Academy of Dermatology, 63 (5), 789-798. [Context Link]