Sudan red or 1-[(2-methoxyphenyl)azo]-2-naphthol is a low molecular weight azoic agent widely used in industry, particularly in the production of hair dyes. The use of this product in the food industry is prohibited due to its potential carcinogenic effect, but no respiratory involvement has been reported to date. We present the case of a 46-year-old female patient who had been working in a cosmetics packaging company for 20 years. The patient developed occupational asthma to a red azo dye known as Sudan red. The diagnosis was confirmed by specific bronchial provocation test. Induced sputum samples were obtained previously and in the 24 h following the procedure, with a rise in the percentage of eosinophils from 10 to 65%. This report describes the case of a patient who developed OA caused by exposure to an azoic dye called Sudan red. The clinical and analytical features suggest a type 2-related asthma; however, we are not yet able to confirm the specific pathophysiological mechanism. The extensive use of azo dyes in industry means that it is particularly important to describe their implications for health, which are probably underestimated at present.