Dear members,

Summarised below are four recent publications which we hope will be of interest including assessment of testing with the 2021/2022 European baseline series and trends in sensitisation to hair care products:

Patch Test Results With the European Baseline Series, 2021/2022—Joint European Results of the ESSCAA and the EBSB Working Groups of the ESCD, and the GEIDACC. W.Uter, S. M.Wilkinson, O.Aerts, et al. Contact Dermatitis (2026): 1–16, doi.org/10.1111/cod.70134.

European surveillance data from 18, 832 patients patch testing with the European Baseline Series (2021- 2022) show largely stable sensitisation patterns, supporting its continued clinical validity. Nickel remains the most common allergen (18.9%), while fragrances continue to contribute a significant burden (13.8% positivity to at least one marker). Preservative allergy persists with MCI/MI and MI positivity (5-5.5%) approaching pre-epidemic levels, and improved detection of formaldehyde at higher concentrations. Of the allergens added to the series in 2019, propolis (5.5%) and 2-hydroxyethyl methacrylate (HEMA, 3.6%) were the most frequently detected. Methyldibromo glutaronitrile (MDBGN) sensitisation remains unexpectedly high despite regulatory bans, whereas parabens and quarternium-15 now show much lower levels, supporting their removal from the 2023 series. Overall, findings reinforce current baseline testing while highlighting allergen trends.

Contact Allergy to Ingredients of Hair Cosmetics Associated with Occupational and Non-Occupational Exposure-Trends from 1995 to 2020 in Central Europe, with or without Regulation.

Uter W, Schwensen JFB, Blömeke B, Gefeller O, John SM, Bieck C, Schubert S. Contact Dermatitis. 2026 Apr;94(4):347-363. doi: 10.1111/cod.70079. Epub 2025 Dec 30. PMID: 41472370; PMCID: PMC12956424.

Long-term IVDK surveillance data (1995–2020) demonstrate that contact allergy to hair cosmetic ingredients remains clinically important, with distinct patterns between occupational (hairdressers) and consumer exposure. Hair dye components, particularly PPD and related intermediates, remain relevant sensitisers with a notable and increasing burden in consumers, whereas trends in hairdressers are generally stable. Increasing sensitisation to toluene‐2,5‐diamine (PTD) in consumers was observed. Several allergens show persistent or rising sensitisation (e.g. hydroquinone), while others illustrate regulatory success, most clearly glyceryl thioglycolate, where sensitisation has clearly fallen in younger cohorts following withdrawal. Bleaching agents (e.g. ammonium persulfate) remain more relevant occupational allergens, whereas preservatives show mixed trends influenced by wider exposure patterns (including the MI epidemic). Overall, the data highlight increasing consumer-driven sensitisation, strong age effects, and variable impact of regulation, underscoring the need for continued surveillance and improved risk management of hair cosmetic ingredients.

Successful treatment of poison ivy dermatitis with upadacitinib.

Tai H, Tang A, Levine J, Talia J, Ungar B. JAAD Case Rep. 2026 Feb 9;70:69-71. doi: 10.1016/j.jdcr.2026.01.053. PMID: 41798158; PMCID: PMC12966863.

This case report describes the successful use of the JAK1 inhibitor upadacitinib in a 54-year-old patient with severe poison ivy (Toxicodendron) allergic contact dermatitis and a background of pityriasis rubra pilaris, on guselkumab. There was rapid resolution of itch and pain within 24 hours of administration of upadacitinib (30mg for 2 weeks followed by 15mg for 2 weeks) and near-complete resolution by 4 weeks. JAK inhibitors block cytokine signalling through the JAK–STAT pathway, reducing activation of multiple T-cell–driven inflammatory axes (Th1, Th2, Th17) central to allergic contact dermatitis. Although limited to a single case, this report suggests a potential role for JAK inhibitors as a therapeutic option in severe cases of allergic contact dermatitis and warrants further study.

Letter: A Case of Propylene Glycol Allergic Contact Dermatitis Associated With Soolantra. Roche D, Nolan B, Twomey N, Golchin R, Bourke J. Dermatitis. 2026 Mar 23:17103568261429237. doi: 10.1177/17103568261429237. Epub ahead of print. PMID: 41869959.

This case describes allergic contact dermatitis secondary to propylene glycol (PG) in a patient with a chronic facial eruption initially managed as rosacea and treated with ivermectin 1% cream (Soolantra). The dermatitis worsened with ongoing use, and patch testing demonstrated a strong positive reaction to PG and PG-containing products (including Soolantra and two cosmetic products). PG, although considered a weak sensitiser, is ubiquitous in topical products and may be under-recognised as a clinically relevant allergen. This report highlights the importance of reviewing excipient ingredients and considering patch testing in patients with persistent or treatment-refractory dermatitis, particularly when symptoms localise to sites of topical application.