Rubber Allergen IPPD Sets Hand Eczema Apart in 6-Year Patch Test Study

More than 4 in 5 patients with hand eczema referred for patch testing at a Shanghai dermatology hospital reacted to at least 1 allergen, with nickel and common cosmetic preservatives topping the list, according to a 6-year retrospective study published in The Journal of Dermatology.¹

Why Hand Eczema Allergen Data Matter

Hand dermatitis accounts for 20% to 35% of all forms of dermatitis and is particularly common in industries that involve wet work or chemical exposure, including cleaning, catering, health care, and hairdressing. Because chronic cases can be driven by irritants, allergens, or both, patients with chronic hand dermatitis may require patch tests to identify a contact allergen they can then avoid.²

Large data sets describing which allergens drive hand eczema in China have been limited, however, and regulatory limits for common sensitizers such as nickel and methylisothiazolinone (MI) differ from those in Europe.¹ The researchers set out to fill that gap by identifying the most common allergens in a large hand eczema cohort and examining how sex, age, history of atopic dermatitis (AD), and occupation shaped sensitization patterns.

A 6-Year, Single-Center Patch Test Cohort

The retrospective cohort study drew on records from the Allergic Dermatoses Clinical Center at Shanghai Skin Disease Hospital. Between 2018 and 2023, 4438 patients with suspected allergic contact dermatitis were patch-tested with cosmetic, eczema, and comprehensive series totaling 85 allergens. Patients with contact dermatitis involving the hands or wrists were classified as having hand eczema, yielding 788 cases (17.76%).

Women made up most of the hand eczema group (n = 554 patients vs 234 men), and 335 patients were older than 40 years. Even so, a far larger share of men than women who were patch-tested had hand eczema (42.47% vs 14.25%; adjusted OR, 4.18; 95% CI, 3.43-5.10), and patients older than 40 years also had higher odds (adjusted OR, 1.40; 95% CI, 1.16-1.69). The analyses were adjusted for age, sex, AD history, and occupation, with false discovery rate (FDR) correction applied for multiple comparisons.

Nickel and Preservatives Topped the Allergen List

In the hand eczema group, 648 patients (82.23%) had at least 1 positive patch test. The 5 most common allergens were nickel sulfate (27.13%), dodecyl gallate (21.45%), MI (20.30%), cobalt chloride (18.34%), and methylchloroisothiazolinone/MI (15.86%). The authors suggested that China's less stringent limits on nickel release from jewelry and on MI in rinse-off cosmetics may contribute to positivity rates higher than those reported in Europe.

N-isopropyl-N-phenyl-4-phenylenediamine (IPPD), a rubber antioxidant used in latex and nitrile medical gloves, was the only allergen that remained significantly more common in patients with hand eczema than in those without hand eczema after FDR correction (2.93% vs 0.51%; adjusted OR, 5.12; 95% CI, 2.59-10.13). Thiuram mix, methenamine, and black rubber mix trended in the same direction before correction. The authors noted that their data spanned the COVID-19 pandemic, and they suggested intensive use of protective equipment may help explain the IPPD signal.

“IPPD represents the principal characteristic allergen distinguishing patients with [hand eczema] from those with [non–hand eczema],” the researchers wrote.

Sex, Age, and Occupation Shaped Sensitization

Polysensitization, defined as reactions to 3 or more unrelated allergens, was more common in women than in men (56.86% vs 44.02%; adjusted P = .004). Men were more often sensitized to occupation-related allergens such as carba mix, a rubber accelerator, while patients older than 40 years showed higher sensitivity to balsam of Peru after FDR correction. A history of AD did not show significant allergen trends, and hand eczema severity did not correlate meaningfully with the number of positive allergens.

Among occupations, hairdressers and beauticians had the strongest association with hand eczema compared with unemployed patients (adjusted OR, 2.76; 95% CI, 1.63-4.66), with higher positivity for preservatives including MI and methylchloroisothiazolinone/MI, as well as p-phenylenediamine, a hair dye ingredient. Food handlers also had higher odds of hand eczema (adjusted OR, 1.86; 95% CI, 1.03-3.36), although most occupation-specific allergen associations did not survive FDR correction.

The data come from a single institution in Shanghai and may not reflect patients across China. Several occupational subgroups were small, which limited interpretation, and the study did not have data directly linking a patient's sensitization to a confirmed workplace exposure. The authors called for long-term, multicenter studies with more balanced samples.

For dermatologists and occupational health programs, the findings reinforce the value of patch testing in hand eczema and point to glove-related rubber chemicals, preservatives, and metals as targets for avoidance counseling and workplace prevention. The authors wrote that the study “supports the application of diagnostic patch testing for better disease and allergen management.”

References

1. Ye C, Gu X, Fei C, et al. Hand eczema referred for patch testing: retrospective study in Shanghai, China from 2018 to 2023. J Dermatol. 2026;53(9):1342-1352. doi:10.1111/1346-8138.70378
2. Oakley A, Koch K. Hand dermatitis (hand eczema). DermNet. Accessed November 2, 2026. https://dermnetnz.org/topics/hand-dermatitis