An allergic/irritant reaction occurring on the skin due to a cosmetic product. Allergic reactions can take days to develop after applying the cosmetic and can last a week or longer even if the product is not used again. Allergies on the skin are typically itchy red often scaling rashes. In contrast, irritation occurs fairly quickly after using a cosmetic and causes burning or stinging with or without redness, depending upon the severity.
Common cosmetic causes of allergic reactions include fragrances, preservatives, emulsifiers, lanolin, and other chemicals present in skin care products, makeups, hair products especially hair dyes, nail care products, sunscreens, toothpastes, mouthwashes, personal cleansing products, shaving preparations, depilatories, epilating waxes, and bath oils/salts.
Irritation is usually due to surfactants (soaps, cleansers), alcohols, or alpha-hydroxy acids (fruit acids) that are contained in some cosmetic products.
Without skin allergy patch testing, it can be very difficult to identify the cause of an allergic reaction, since it occurs days after exposure and can last for many days after it appears. Sometimes, you can identify offending products by recalling whether you have used any new products, had new procedures preformed, such as hair dye or placement of artificial nails. Discontinuing the use of all suspicious cosmetic products, followed by adding one product back at a time to your cosmetic routine every two weeks, may reveal which product is the offending agent, because most products will cause a skin reaction within a two week period. However, this will not tell you what chemical in the product is the problem; this chemical is likely used in many other cosmetic products. So, skin allergy patch testing is the best way to determine the cause. Also, it is not unusual that you can develop an allergy to a product that you have used for many years. Why this happens is not clear – but it does!
Irritation is easier to identify as it occurs almost immediately after using a product. Check the label for alcohols or alpha-hydroxy acids and avoid future products containing these chemicals. Patients with rosacea are particularly prone to cosmetic irritation..
Avoiding any known or suspected offending agent is key. Avoiding fragrances, or other non-essential chemicals often added to products may be helpful. It is also recommended that all old cosmetic products be thrown out, as the ingredients/formulas may alter with age. Over the counter cortisone creams may be beneficial for itchy symptoms, and your dermatologist may prescribe a stronger steroid medication for your symptoms if needed. To identify the exact cause of your reaction, allergy patch testing is recommended.