Contact dermatitis due to cosmetic products is a common dermatologic complaint that considerably affects the patient's quality of life. Diagnosis, treatment, and preventive strategies represent a substantial cost. This condition accounts for 2% to 4% of all visits to the dermatologist, and approximately 60% of cases are allergic in origin. Most cases are caused by skin hygiene and moisturizing products, followed by cosmetic hair and nail products. Fragrances are the most common cause of allergy to cosmetics, followed by preservatives and hair dyes; however, all components, including natural ingredients, should be considered potential sensitizers. We provide relevant information on the most frequent allergens in cosmetic products, namely, fragrances, preservatives, antioxidants, excipients, surfactants, humectants, emulsifiers, natural ingredients, hair dyes, sunscreens, and nail cosmetics.