A topical approach to relieving itch is particularly helpful for pruritus resulting from skin damage, inflammation, or dryness (Yosipovitch, 2003). Treatments commonly used include those that restore and preserve the barrier function of skin, such as emollients and low pH cleansers and moisturizers, as well as several additional topical applications. These include cooling agents, topical anesthetics, topical antihistamines, capsaicin, topical corticosteroids, and topical immunomodulators.
Emollients are the first-line therapy for pruritus. While they are generally not considered antipruritics, they can help reduce itch, particularly in patients with xerosis (dry skin) (Ronayne, Bray, & Robertson, 1993). Xerosis is the most common cause of pruritus without an accompanying rash, and it can be associated with inflammatory skin diseases including atopic dermatitis, systemic diseases such as hypothyroidism, and with normal aging (Fleischer, Feldman, Katz, & Clayton, 2000; Millikan, 1996). Alterations in the barrier function of dry skin, such as stratum corneum abnormalities in keratinization, surface lipid content, and water content may contribute to the sensation of itch (Elias & Ghadially, 2002). Emollients help restore this altered barrier function. Water normally evaporates from the skin surface quickly, but emollients contain lipids and other substances which seal in moisture. They should be applied immediately after bathing to promote hydration of the skin by preventing transepidermal water loss (Wahlgren, 1999). Not all emollients are equally effective in restoring barrier function. A recent study using a ceramide-dominant lipid-based emollient in patients with atopic dermatitis demonstrated that it significantly reduced the severity of disease when substituted for other moisturizers (Chamlin et al., 2002). Stratum corneum cohesion and hydration improved in these patients, which is evidence of barrier function restoration. While the study did not specifically evaluate pruritus, this type of emollient may be useful in treating itch related to xerosis and altered barrier function.
Low pH cleansers and moisturizers are useful in maintaining the acidic pH of the skin surface, which helps to preserve barrier function (Yosipovitch & Hu, 2003). The acidic skin surface is important in reducing skin irritation, which ultimately helps to reduce itch. High skin surface pH has been noted in xerosis, atopic dermatitis, and uremia (Yosipovitch & Maibach, 1996).
Cooling agents are over-the-counter preparations which usually contain menthol, camphor, or phenol (Yosipovitch, 2003). These substances stimulate nerve fibers which transmit the sensation of cold, thereby masking the itch sensation. Cooling agents are reasonably safe, although applying large amounts of alcohol-containing preparations can irritate the skin (Fleischer, 2000).
Topical anesthetics, including pramoxine and EMLA (eutectic mixture of local anesthetics) cream, have a documented antipruritic effect (Shuttleworth, Hill, Marks, & Connelly, 1988; Yosipovitch & Maibach, 1997). These are most useful for mild-to-moderate pruritus, and they may be combined with coolants to heighten effectiveness (Millikan, 1996).
Topical antihistamines, which block H1-receptors, are effective as antipruritics, particularly when used for urticaria and insect bites. Doxepin is perhaps the most effective topical antihistamine, although its use is limited by the occurrence of allergic contact dermatitis and sedation from percutaneous absorption (Drake, Fallon, & Sober, 1994; Shelley, Shelley, & Talanin, 1996).
Capsaicin is useful in relieving itch associated with many conditions, particularly intractable pruritus at a localized site (Hagermark & Wahlgren, 1995). It is the potent component of cayenne or red peppers, and acts by desensitizing nerve endings responsible for itch and pain (Yosipovitch, 2003). It may cause localized burning and stinging which limits its use as an antipruritic. This irritation subsides with repeated use of capsaicin, but patients may have difficulty maintaining compliance. It is helpful if patients initially use capsaicin four times per day to overcome the irritation, then they may reduce the number of daily applications. The topical anesthetic, EMLA cream, may be used in conjunction with capsaicin to reduce the initial irritation (Yosipovitch, Maibach, & Rowbotham, 1999).
Topical corticosteroids may indirectly provide relief of itch associated with inflammatory skin diseases such as atopic dermatitis, but they should not be used to treat generalized itch. Potential side effects of long-term application of topical corticosteroids include skin atrophy, cutaneous eruptions, and dryness (Fleischer, 2000). They are not intended for long-term use.
Topical immunomodulators inhibit T-lymphocyte activation thereby reducing inflammation and indirectly decreasing itch. Tacrolimus topical preparation significantly reduces inflammation and pruritus in patients with atopic dermatitis with little resultant toxicity (Fleischer, 1999). The role of tacrolimus as an antipruritic for other pruritic states is not clear.
There are some topical applications that are effective for itch reduction but are not commercially available in the United States. One of these is topical aspirin, which is effective in treating experimentally induced itch (Yosipovitch, Ademola, Lui, Amin, & Maibach, 1997) as well as itch associated with severe lichen simplex chronicus, a form of localized pruritus (Yosipovitch et al., 2001). Of note, orally administered aspirin does not reduce itch (Daly & Shuster, 1986). Also not available in the United States is a topical antipruritic derived from the Amazonian herbal medicine sangre de grado, which can reduce itch associated with insect bites (Miller et al., 2001). Naturally derived substances may have a role in managing pruritus in the future. Finally, in Europe, there is extensive use of moisturizers that are combined with topical antipruritics such as polidocanol and menthol. This approach is not commonly used in the United States.
The use of wet-wrap dressings in patients with refractory atopic dermatitis can reduce itching and promote healing (Bridgman, 1995). Emollients or corticosteroid dilutions are applied to affected skin and then covered with occlusive wet dressings (Wolkerstorfer, Visser, De Waard van der Spek, Mulder, & Oranje, 2000). Side effects are minimal and this provides one more option for managing this disorder.
Dermatology Nursing. 2004;16(4) © 2004 Jannetti Publications, Inc.
Cite this: Practical Guidelines for the Relief of Itch - Medscape - Aug 01, 2004.