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Direct cutaneous exposure to chemical or physical agents causes contact dermatitis (CD). Acute inflammation is typically worse with each subsequent incident, because sensitivity to the offending agent builds through anamnestic memory T cells.¹

Itch leads the list of symptoms emanating from the characteristic erythematous rash along with bumps, blisters, wheals, welts, dryness, fissuring, vesicles, bullae, lichenification, hives, urticaria and edema, as well as the possibility of secondary bacterial infection and cellulitis from excessive scratching or a contaminated environment. CD is not a contagious or terminal condition, but discomfort, insomnia, employment loss—particularly in health-care positions—and poor quality of life are common, especially in chronic cases where exposure cannot be eliminated.

Classifications of CD

Allergens incite allergic CD, driven by delayed-type hypersensitivity,² whereas environmental chemicals incite irritant CD, constituting 80% of all cases.³ Common irritants include nickel, balsam, thimerosol, neomycin and fragrances. Both conditions can become phototoxic when exacerbated by sunlight. Of all occupational cutaneous presentations, 95% are diagnosed as CD,³ and the most common site for presentation is the hands. Specifically, urushiol CD from the sap of toxicodendron or rhus plants (poison ivy, oak or sumac) generates 43,000 emergency room visits annually in the United States.⁴ Histopathologically, CD involves localized inflammation in the epidermis and outer dermis.⁵

Clinical Course

While allergic CD heals in days or weeks, contact urticaria hives appear instantaneously within minutes after exposure and resolve within minutes to hours thereafter. Prolonged exposure may significantly delay healing. Occasionally, chronic CD persists even after eliminating the inciting agent or toxin. Irritant CD remains confined to the directly exposed skin, while allergic CD often spreads.

Treatment

Vigorous washing with soap and cool water can eliminate most of the offensive substance immediately upon exposure to a recognized irritant or allergen. The following options for patient-initiated care can also help:

• Cold moist compresses.
• Calamine lotion.
• Calamine lotion with diphenhydramine (Benadryl).
• Zinc oxide barrier cream (Desitin).
• Topical OTC 1% hydrocortisone cream.
• Topical weak acids such as lemon vinegar or lemon juice.
• Oral OTC antihistamines such as diphenhydramine, chlorpheniramine, cetirizine, fexofenadine, hydroxyzine, loratadine or promethazine.
• Behavioral interventions such as wearing gloves and clipping fingernails to reduce scratching.

For severe or recalcitrant cases, physician intervention with stronger topical steroids (for example, triamcinolone 0.1% or clobetasol 0.05%) or slowly weaned oral steroids (namely, prednisone 0.5 to 1 mg/kg in the morning with food) for up to 21 days may be necessary.⁴ Some cases have reported successful dupilumab use.^6,7

Periocular CD may create temporary visual disability due to severe occlusive ptosis. In these cases with lid involvement, a topically applied preservative-free steroid such as loteprednol etabonate 0.5% ointment (Lotemax, Bausch + Lomb) or judicious off-label topical pimecrolimus 1% cream (Elidel) have been useful.⁸

Severe mucous membrane CD may also follow exposure to rhus plant sap. Conjunctival involvement responds to supplementary prescription topical therapy with steroids (such as loteprednol etabonate or prednisolone acetate), antihistamines (olopatadine, azelastine, ketotifen or bepotastine besilate) or dry eye medications (chilled preservative-free artificial tears, cyclosporine, lifitegrast [Xiidra, Bausch + Lomb] or perfluorohexyloctane [Miebo, Bausch + Lomb]). Long-term use of topical adrenergic receptor agonist vasoconstrictors such as naphazoline, tetrahydrozoline, phenylephrine or oxymetazoline should be avoided.

Prevention

Toxin or allergen identification and avoidance are, by far, the most effective means to prevent CD.⁹ Sensitized individuals should be patch tested to guide lifestyle changes,¹⁰ including reduced tobacco smoke exposure,¹¹ and patient and family education on sensitivities is advised. Workplace modifications, protective clothing and gloves can reduce CD incidence and severity.

If direct exposure occurs to a previously inciting agent such as poison ivy, urushiol oil can be immediately removed from skin and fingernails with soapy lukewarm water, rubbing alcohol (70% isopropyl alcohol), dishwashing liquid, or Tecnu®️ (Deodorized Mineral Spirits, Water, Propylene Glycol, Octylphenoxy-Polyethoxyethanol, Mixed Fatty Acid Soap).

References: 

1. Rustemeyer T. Immunological mechanisms in allergic contact dermatitis. Curr Treat Options Allergy. 2022 Apr;9:67–75. doi:10.1007/s40521-022-00299-1
2. Cohen DE, Heidary N. Treatment of irritant and allergic contact dermatitis. Dermatol Ther. 2004;17(4):334–340. doi:10.1111/j.1396-0296.2004.04031.x
3. Bains SN, Nash P, Fonacier L. Irritant Contact Dermatitis. Clin Rev Allergy Immunol. 2019 Feb;56(1):99–109. doi:10.1007/s12016-018-8713-0
4. Butt M, Flamm A, Marks JG, Flamm A. Poison ivy dermatitis treatment patterns and utilization: a retrospective claims-based analysis. West J Emerg Med. 2022 Jun;23(4):481-488. doi:10.5811/westjem.2022.March.55516
5. Novak-Bilić G, Vučić M, Japundžić I, Meštrović-Štefekov J, Stanić-Duktaj S, Lugović-Mihić L. Irritant and allergic contact dermatitis-skin lesion characteristics. Acta Clin Croat. 2018 Dec;57(4):713-720. doi:10.20471/acc.2018.57.04.13.
6. Slodownik D, Levi A, Lapidoth M, Moshe S. Occupational chronic contact dermatitis successfully treated with dupilumab: a case series. Dermatology. 2022;238(6):1073-1075. doi:10.1159/000524380
7. Olbrich H, Sadik CD, Ludwig RJ, Thaçi D, Boch K. Dupilumab in inflammatory skin diseases: a systematic review. Biomolecules. 2023 Mar;13(4):634. doi:10.3390/biom13040634
8. Di Staso F, Lambiase A, Di Staso S, Gattazzo I, Ciancaglini M, Scuderi G. Topical treatment of dupilumab-associated refractory conjunctivitis and keratitis. Am J Ophthalmol Case Rep. 2022 Jan;25:101309. doi:10.1016/j.ajoc.2022.101309
9. Usatine RP, Riojas M. Diagnosis and management of contact dermatitis. Am Fam Physician. 2010 Aug;82(3):249-255.
10. Warshaw EM, Buonomo M, DeKoven JG, et al. Importance of supplemental patch testing beyond a screening series for patients with dermatitis: the North American Contact Dermatitis Group experience. JAMA Dermatol. 2021 Dec;157(12):1456-1465. doi:10.1001/jamadermatol.2021.4314
11. Alotaibi GF, Alsalman HH, Alhallaf RA, et al. The association of smoking with contact dermatitis: a cross-sectional study. Healthcare (Basel). 2023 Feb;11(3):427. doi:10.3390/healthcare11030427