Allergic contact dermatitis (ACD) is a dermal inflammatory disease caused by allergic reactions to substances that contact the skin. The hyperactivation of T cells plays an important role in its pathogenesis. Photobiomodulation (PBM) is an efficacious therapeutic approach for suppressing inflammatory diseases.

Patch test results may be influenced by age-related factors. However, there is still discordant evidence between age and patch test results.

Rubber gloves contain rubber accelerators that may cause contact allergy. The content of sensitising rubber accelerators in contemporary rubber gloves is not well known.

Dicyclohexylcarbodiimide (DCC) is known to cause occupational allergic contact dermatitis in biotechnology laboratory workers.

Propolis types differ regarding their chemical composition.

Cutaneous reactions to povidone (PVP)-iodine are widely reported; however, distinction between allergic and irritant reactions can be challenging. Free iodine is responsible for irritant reactions and is released when PVP-iodine is in a liquid state. The aim of this study was to review the clinical presentation and results of patch testing in patients with PVP-iodine contact dermatitis. A systematic review was conducted by searching Pubmed, MEDLINE, and Google Scholar databases for reports of contact dermatitis secondary to PVP-iodine. Data were collated including study design, patient age and gender identity, iodine exposure, skin biopsy findings, and patch test methodology and results. The search revealed 187 reports with 38 eligible studies; 30 case reports/case series and 8 retrospective cohort studies. Overall, there were 223 patients with PVP-iodine contact dermatitis. The commonest reaction was irritant contact dermatitis (51%), followed by allergic contact dermatitis (40%) and contact dermatitis not further specified (9%). Irritant reactions were characterised by burn-like morphology and, when due to surgical skin disinfectant, were often distant from the surgical incision site. Patch testing was most often performed with a 10% PVP-iodine aqueous solution; however, irritant reactions in controls occur. Various testing methods including iodine in petrolatum, ethanol, dried powder, and open application testing were described. Most reactions to PVP-iodine are irritant and patch testing using a closed-chamber method yields inconsistent results due to risk of irritation from free iodine release over the 2-day occlusion time. Surgeons should be aware of the risk of prolonged skin contact with wet iodine solution.

Hair dyes are widely used in daily life. However, data on self-reported adverse skin reactions are scarce.

Limonene and linalool are used in cosmetic products for their floral scents, but their oxidation products are strong contact allergens whose mechanisms of action are still not fully understood.

The Hand Eczema Severity Index (HECSI) is a Clinician-Reported Outcome measure of the severity of hand eczema (HE).

Rubber accelerators are used in the vulcanization of rubber. However, rubber accelerators for example tetraethylthiuram disulfide (TETD) and zinc diethyldithiocarbamate (ZDEC) may cause contact allergy. Concomitant reactions between ZDEC and TETD have been observed in patients which could be explained by co- or cross-reactivity.