A subset of people feel stinging and burning when exposed to certain skin care products. These people have traditionally been called “stingers” since Kligman coined the term in 1977. This skin type has also been called reactive skin, hyperreactive skin, intolerant skin, or irritable skin. In the Baumann Skin Typing System, stingers are designated as having Baumann S3 sensitive skin (see Chapter 9); the “3” denotes burners and stingers rather than other types of sensitive skin that develop such as acne (S1), rosacea (S2), or contact dermatitis (S4). One patient can demonstrate one to four different types of sensitive skin. For example, many rosacea (S2) patients are also burners and stingers (S3). Although this skin type is referred to as stingers in the context of applying chemical factors such as skin care ingredients, this skin type also includes those who feel the onset of a prickling, tingling sensation, or slight pain because of physical factors such as ultraviolet radiation, heat, cold, and wind. Psychologic stress or hormonal factors such as menstruation may play a role as well. It is important to know a patient’s susceptibility to S3 sensitive skin because this may lead to noncompliance with certain medications and vehicles that cause discomfort to the patient. Finacea is an example of a rosacea medication that causes stinging in a small proportion of users. Retin A Micro contains benzyl alcohol (a derivative of benzoic acid) that can cause stinging in certain people. This chapter will discuss what is known about the mechanisms of burning and stinging, what ingredients are most likely to cause it, and how to identify a potential “stinger.”
Type 3 sensitive skin is common worldwide. In a British study, 57% of women and 31.4% of men reported that they had experienced an adverse reaction to a personal skin care product at some stage in their lives, with 23% of women and 13.8% of men having had a problem in the last 12 months.1 Another study demonstrated that women showed a greater tendency toward being more sensitive to the subjective effects elicited by lactic acid than males.2
MECHANISMS OF BURNING AND STINGING
Stinging is a problem reported to occur primarily on the face, particularly on the nasolabial folds and cheeks. The extreme sensitivity of this region is thought to be caused by a more permeable horny layer, a high density of sweat glands and hair follicles, and an elaborate network of sensory nerves.3 There is specificity of the stinging response that is not understood. In other words, an individual may be a lactic acid stinger, but not experience such a reaction to other ingredients such as benzoic acid and azelaic acid. One study showed that there was no correlation between patients who stung from lactic acid and those who stung from azelaic acid.4 This suggests that there is ...