BACKGROUND: Carmine is a natural red dye that may cause allergic contact dermatitis. OBJECTIVE: The aim of this study was to analyze patch test reactions to carmine (2.5% in petrolatum) and characterize carmine-positive patients. METHODS: This study conducted a retrospective analysis of North American Contact Dermatitis Group data compiled between 2011 and 2012. RESULTS: Of 4240 patients patch tested to carmine, 132 (3.1%) had reactions with a final interpretation of "allergic" (positive). Carmine-positive patients were significantly more likely to be female (77.7% vs 68.3%; P = 0.0237) and have a final primary diagnosis of allergic contact dermatitis (74.8% vs 47.2%; P < 0.0001). As compared with carmine-negative patients, carmine-positive patients were significantly more likely to have involvement of all facial sites combined (48.1% vs 29.9%; P < 0.0001) and the lips (7.6% vs 3.6%; P = 0.0166). At final reading, most carmine reactions were weak (+; 64.9%). Approximately half (53.4%) were currently clinically relevant; identified sources were primarily personal care products (77.1%), especially makeup (31.4%) and lip products (8.6%). CONCLUSIONS: Weak patch test reactions to carmine should be interpreted with caution. Allergic contact dermatitis to carmine should be suspected in women with facial and/or lip dermatitis, especially those using carmine-containing cosmetics.