Colophony (rosin) is a prevalent cause of contact allergy and allergic contact dermatitis (ACD). It exists in both unmodified and modified forms and is widely present in everyday products, making exposure difficult to avoid. Common applications include printing ink, adhesives, sealants, and paper sizing. Due to its sensitizing properties, colophony is classified as a skin sensitizer (Category 1), requiring labeling when present in concentrations of 0.1% or higher. Products containing at least 1% must carry the warning “H317: May cause an allergic skin reaction.” Modified rosins may still cause allergenic reactions due to residual unmodified rosin or new allergenic derivatives such as maleopimaric acid. Further research is needed to investigate the presence of modified rosins in various products and to assess their role in ACD prevalence among dermatitis patients and the general population.