Eczema Pop Quiz: Contact Dermatitis Edition
Test your knowledge to see if you know these surprising facts about contact dermatitis.
Published On: Dec 4, 2024
Last Updated On: Dec 4, 2024
If you’ve broken out in an itchy rash at the same location where you wore a ring, belt buckle or a piece of clothing, you’ve likely had contact dermatitis. Contact dermatitis is a type of eczema — it’s different from atopic dermatitis (AD), the most common type of eczema. But it’s possible to have both contact dermatitis and AD. Contact dermatitis is caused by an allergic reaction after an allergen or irritant touches your skin. Contact dermatitis affects about 15% of the global population1 and over 14 million Americans each year.2
In your everyday life, you likely run into ingredients that could cause contact dermatitis. For example, chemicals at work, personal care products at home, diapers and toys in childcare settings, gloves and masks in healthcare settings or plants like poison ivy while gardening or hiking.2-11 So, what are the common allergens and irritants that cause contact dermatitis? How is it diagnosed and what are the treatment options?
“The most important thing for patients to understand is that contact dermatitis is treatable,” said Dr. Margo Reeder, an associate professor of dermatology and practicing dermatologist at the University of Wisconsin. “The first step is identifying the culprit. If we can identify the problem, then we can teach you how to avoid it and the skin can become clear of symptoms.”
Contact dermatitis is an itchy, inflammatory skin disease. It is caused by an inflammatory response to contact between the skin and an ingredient or object that a person is either allergic to or that is irritating to the skin.10 You can develop contact dermatitis anywhere on the body that comes in contact with allergens, including hands, feet, scalp, face, arms, legs, chest, abdomen and genitals.12
There are two main types of contact dermatitis: allergic contact dermatitis and irritant contact dermatitis. Allergic contact dermatitis arises from an allergic immune reaction, meaning your immune system has a reaction. It can be a delayed reaction that appears as a rash a day or two after skin is exposed to an allergen, such as poison ivy. Irritant contact dermatitis is more closely related to direct chemical injury to the epidermis. It happens when skin cells are damaged by exposure to irritating substances, like soaps or hair dye. The immune system is activated, whether the ingredient causes an allergy or is related to the skin barrier.1,13
You can even develop contact dermatitis from things you’ve been in contact with for years or your entire life. “Patients often say, ‘How can I be allergic to this? I’ve been using it for years!’” explained Dr. Jonathan Silverberg, one of the world’s leading experts on contact dermatitis and a dermatologist at George Washington University. “Contact dermatitis can develop slowly and it is not always an immediate reaction after exposure. In particular, with things like personal care products, applying them to inflamed skin with a reduced barrier can actually lead to the immune system mounting the reaction that leads to contact dermatitis. It doesn’t happen all at once.”
When it comes to who gets contact dermatitis, very little is currently known about whether there are differences in the reactive agents that cause it or the severity of reactions in people from different racial and ethnic backgrounds.14 One U.S. study found that Asian and Hispanic children saw more providers prior to undergoing patch testing, meaning it took longer for them to figure out the culprits and be able to avoid them. Further, Black children were tested with fewer potential allergens during patch testing compared to white children, meaning important items of contact may have been missed.14 More studies that specifically include patients from different racial and ethnic groups are needed to understand and reduce disparities in underrepresented populations.14
Contact dermatitis can be diagnosed by physicians through medical history and patch testing. To take your medical history, your healthcare provider will ask you lots of questions about your daily life and products you come into contact with regularly. “We have to do a lot of sleuthing to figure out where patients are getting exposed to the things causing their contact dermatitis symptoms,” said Dr. Silverberg.
To rule out or confirm what could be causing contact dermatitis, healthcare providers may ask about a patient’s job, hobbies, medications, topical cosmetics or other things applied to the skin and fabrics worn. It is very important that a physician take a thorough history of what an individual may be exposed to so that the patch testing can contain the right allergens and irritants to be as helpful as possible.5
Patch testing is a process where patches containing small amounts of suspected allergens or irritants are applied to a patient’s back. The patches are usually left on for one or two days. Then they are “read” by an experienced patch testing dermatologist to determine which ingredients cause the strongest reactions. A list of ingredients and products to avoid can then be created, helping the patient prevent a contact dermatitis rash.
Most patch test kits include common culprits, but providers can often add specific ingredients to test for a suspected allergen. For example, if you suspect a specific makeup brand’s ingredient is causing the issue, they can add it as one of the patches.
Patch testing is approved by the Food and Drug Administration (FDA) for adults and children.15 While adults can get basic patch testing with a few dozen allergens, they can also have more complex and expanded testing with hundreds of potential reactionary allergens and irritants placed on their backs. Small children may have as few as 30 to 38 allergens applied since they likely haven’t come into contact with as many ingredients and components in their lives.15 Plus, their backs are small so only a few patches can be applied at one time.15
“In general, we don’t patch test kids as frequently as adults and may therefore be missing kids that have contact dermatitis,” said Dr. Reeder. “Kids may be misdiagnosed with AD when, if they got patch testing, they may be able to avoid an irritant and experience clearing of their symptoms. Patch testing can be really valuable to families.”
Although patch testing is a standard diagnosis tool for contact dermatitis, it is not always available to all patients due to insurance coverage or needing a specialized clinic that is only available in certain parts of the country or world. “In a perfect world we would be able to patch test everyone, but in reality, this is not easy to do,” said Dr. Silverberg. “Some patients need really complex, expanded patch testing due to their potential contacts and there are very few places in the U.S. that do complex patch testing.”
Patch testing can get more complicated if the patient also has AD. “They may have AD lesions on their back, which is where the allergens and irritants are applied via patches for patch testing,” Dr. Silverberg explained. “We can’t patch test on an already inflamed region. Ideally, before patch testing, a patient should be clear of back wounds, off topical therapies for at least a week or two and off biologic therapies — this is often not feasible at all for patients.”
If patch testing is not available, healthcare providers can take a very thorough patient history, asking lots of questions about things each patient comes into contact with to help narrow down culprits.
There are two major organizations of healthcare professionals and medical researchers, the North American Contact Dermatitis Group and the American Contact Dermatitis Society, who work to identify and understand the expanding list of ingredients and objects that can lead to contact dermatitis. These organizations aim to raise awareness of the causes of contact dermatitis, while also performing research and keeping an eye out for new culprits as they arise.
Allergens and irritants that cause contact dermatitis are constantly in flux, changing with trends in industry, occupations and consumer habits.8 Every year, new agents that cause contact dermatitis are reported after being found in cosmetics and personal care products.8 For the last few decades, both the North American Contact Dermatitis Group and the American Contact Dermatitis Society have named an “allergen of the year.” This helps both healthcare providers and the general public understand what products contain the featured ingredients and how to avoid them. These “allergens of the year” can help healthcare providers know what emerging irritants to include in patch testing, but there are tens of thousands of possible ingredients that can cause contact dermatitis.
So which ingredients have made the allergen of the year list? Here are some of the most common allergens that lead to contact dermatitis:
“Many people are looking toward more natural products to try to cut down on exposure to allergens, but natural and botanical ingredients are some of the biggest culprits for contact dermatitis,” Dr. Silverberg said. “Sometimes the best products are those that have very few ingredients. But patients should be aware that natural does not mean allergen free — poison ivy is natural.”
Even the term hypoallergenic is not regulated by any clinical or market standards, so people should be careful before using these products.7
Adults typically encounter allergens and irritants in products like hairspray, colognes, perfumes and other cosmetics. “Adults have often been using their products for a long time and tend to have a rash locally where the skin contact occurs,” Dr. Silverberg said. “In contrast, children are more likely to develop what is called an ‘id’ reaction, which means that they may be exposed to a product on one part of their body but then get an expanded, more generalized skin rash all over.”
A systematic review of scientific literature on toys that cause contact dermatitis identified several common offenders. For example, toys such as electronics (like video game controllers), toy cars, costume jewelry, bicycles, slime and children’s clay were mentioned.16
The most common ingredient causing contact dermatitis in children is nickel.16 Nickel can be an allergen for both children and adults and is often found in toys and electronic devices like cell phones, iPads and computers.16
Personal care products like shampoo, conditioner, hairspray, shaving cream, sunscreen, mascara, and even baby lotion and baby shampoo can contain a chemical called methylchloroisothiazolinone or methylisothiazolinone.16 These chemical names represent ingredients that a person with contact dermatitis, or their caregivers, need to recognize if they are causing the disease symptoms.
Other studies have shown that nickel, cobalt, neomycin, myroxylon pereirae (balsam of Peru), fragrance mix I, fragrance mix II, formaldehyde and lanolin are the most common causes of contact dermatitis in children. Essential oils, lotions and shampoos can contain some of these ingredients and some can even be found in textiles used in furniture and clothing.2 Unfortunately, there are a lot of ingredients to watch out for and this is why patch testing can be so crucial. It’s one way to rule out products that have the ingredients that are causing the allergy or irritant reaction.
There is evidence that AD and contact dermatitis can coexist and that patients with AD may even be more sensitive to allergens and irritants that cause contact dermatitis.17 The current thought among researchers is that active AD — with inflamed skin and a compromised skin barrier — can result in an increased possibility that allergens and irritants will trigger even more inflammation.18 However, it can be challenging to separate one type of dermatitis from another in order to do clear research.18
Dr. Reeder mentioned three things to look for that may indicate a person has contact dermatitis, in addition to or instead of AD. They are:
If these things occur, a patient should talk to their healthcare provider about doing thorough analysis to find possible culprits underlying contact dermatitis.18
It is very important to note that if AD and contact dermatitis coexist, AD treatments can be less effective because the patient may continuously be exposed to factors that cause rashes associated with contact dermatitis.17 “It can be important to rule out contact dermatitis in patients before moving from topical to systemic therapies to treat AD,” Dr. Silverberg said. “It may not be beneficial to start taking systemic AD therapies if avoiding exposure to something could clear up some of the symptoms instead.”
The number one goal for preventing and treating contact dermatitis symptoms is to avoid contact with the culprit agent (or irritant).19 After determining what those agents or ingredients are, it’s crucial to determine which products or objects may be causing the contact dermatitis symptoms. One way to figure out products that might have these ingredients is through the American Contact Dermatitis Society. They maintain and regularly update a large database of products in their Contact Allergen Management Program (CAMP). Healthcare providers who are members of the American Contact Dermatitis Society can access this database, which is currently being expanded to contain over 100,000 products, and give patients access to their personal “avoid” list from this database.
“Once a patient has undergone patch testing or found out their culprits, it is very important to become familiar with the names (sometimes very long, complex names) of the ingredients causing contact dermatitis,” Dr. Reeder said. “Read labels on products to be sure the product does not contain that ingredient.”
Sometimes avoidance of the culprit chemical is as easy as switching shampoos or soaps. However, other times it is nearly impossible to avoid the problem. For example, if the irritating fragrance is in the environment, or the allergen is an ingredient in a necessary medical device like an insulin monitor. Another difficult situation is when the irritant is something the person comes into contact with every day at work.19 In these cases, further treatment may be required like topical or systemic steroid therapy.19 When it’s not possible to avoid the product, some of the same systemic therapies being used to treat AD can also be employed for treating contact dermatitis.19 This can be problematic as the immune reaction is ongoing every time a person comes in contact with the agent, so the treatment may have to be very long-term, which can lead to unwanted side effects.19
A few research groups are also working to develop topical hydrogels for contact dermatitis. These hydrogels are designed to be applied prior to exposure to an ingredient, or even put into products like cosmetics, to help reduce the allergic reaction.12,20 These research groups have found that certain ingredients like lysine and N-acetyl cysteine can form barriers between an allergen and the skin.20 These hydrogels must still be tested broadly in humans to make sure that they themselves do not lead to immune reactions.12
If a large number of people are having an allergic reaction to an individual product or ingredient, the FDA might be notified. Even if the FDA isn’t aware, manufacturers might notice there is an issue when customers stop buying their product. For example, wet wipes used to have ingredients like methylisothiazolinone that caused contact dermatitis. This ingredient has now been removed. “Sometimes enough people react to a product and stop buying it, which leads manufacturers to make changes so their products can be sold again,” said Dr. Reeder. Consumers can impact companies to change products or ingredients.
References:
1. Azeem M, Kader H, Kerstan A, et al. Intricate Relationship Between Adaptive and Innate Immune System in Allergic Contact Dermatitis. Yale J Biol Med. 2020;93(5):699-709.
2. Militello M, Hu S, Laughter M, Dunnick CA. American Contact Dermatitis Society Allergens of the Year 2000 to 2020. Dermatol Clin. 2020;38(3):309-320.
3. Chamani S, Mobasheri L, Rostami Z, Zare I, Naghizadeh A, Mostafavi E. Heavy metals in contact dermatitis: A review. J Trace Elem Med Biol. 2023;79:127240.
4. Clement A, Ferrier le Bouedec MC, Crepy MN, et al. Hand eczema in glove-wearing patients. Contact Dermatitis. 2023;89(3):143-152.
5. Clynick M, Holness DL. New causes of occupational allergic contact dermatitis. Curr Opin Allergy Clin Immunol. 2024;24(2):51-57.
6. DeKoven JG, DeKoven BM, Warshaw EM, et al. Occupational contact dermatitis: Retrospective analysis of North American Contact Dermatitis Group Data, 2001 to 2016. J Am Acad Dermatol. 2022;86(4):782-790.
7. Hiranput S, McAllister L, Hill G, Yesudian PD. Do hypoallergenic skincare products contain fewer potential contact allergens? Clin Exp Dermatol. 2024;49(4):386-387.
8. Milam EC, Cohen DE. Clinically relevant contact allergens in the modern era. Ann Allergy Asthma Immunol. 2019;123(6):539-541.
9. Ryczaj K, Dumycz K, Spiewak R, Feleszko W. Contact allergens in moisturizers in preventative emollient therapy – A systematic review. Clin Transl Allergy. 2022;12(6):e12150.
10. Tramontana M, Hansel K, Bianchi L, Sensini C, Malatesta N, Stingeni L. Advancing the understanding of allergic contact dermatitis: from pathophysiology to novel therapeutic approaches. Front Med (Lausanne). 2023;10:1184289.
11. Zemelka-Wiacek M. Metal Allergy: State-of-the-Art Mechanisms, Biomarkers, Hypersensitivity to Implants. J Clin Med. 2022;11(23).
12. Brites GS, Ferreira I, Sebastiao AI, et al. Allergic contact dermatitis: From pathophysiology to development of new preventive strategies. Pharmacol Res. 2020;162:105282.
13. Yamaguchi HL, Yamaguchi Y, Peeva E. Role of Innate Immunity in Allergic Contact Dermatitis: An Update. Int J Mol Sci. 2023;24(16).
14. Young K, Collis RW, Sheinbein D, et al. Retrospective review of pediatric patch testing results in skin of color. J Am Acad Dermatol. 2023;88(4):953-954.
15. Tam I, Yu J. Pediatric contact dermatitis: what’s new. Curr Opin Pediatr. 2020;32(4):524-530.
16. Fenner J, Hadi A, Yeh L, Silverberg N. Hidden risks in toys: A systematic review of pediatric toy contact dermatitis. Contact Dermatitis. 2020;82(5):265-271.
17. Johnson H, Novack DE, Adler BL, Yu J. Can Atopic Dermatitis and Allergic Contact Dermatitis Coexist? Cutis. 2022;110(3):139-142.
18. Spiewak R. Contact dermatitis in atopic individuals. Curr Opin Allergy Clin Immunol. 2012;12(5):491-497.
19. Yin L, Ungar B, Guttman-Yassky E, Cohen DE, Karagounis TK. Beyond Avoidance: Advanced Therapies for Contact Dermatitis. J Allergy Clin Immunol Pract. 2024.
20. Brites G, Basso J, Miranda M, Miguel Neves B, Vitorino C, Cruz MT. Development of a new hydrogel for the prevention of allergic contact dermatitis. Int J Pharm. 2022;628:122265.
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