How To Detect And Treat Pruritus
- Volume 19 - Issue 8 - August 2006
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Capsaicin is useful in relieving itch associated with many conditions, particularly intractable pruritus at a localized site. It has the potent component of cayenne or red peppers, and acts by desensitizing nerve endings responsible for itch and pain. 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. If patients initially use capsaicin four times per day to overcome the irritation, then the number of daily applications may decrease. One may use the topical anesthetic, EMLA cream, in conjunction with capsaicin to reduce the initial irritation.
Topical corticosteroids may indirectly provide relief of itching associated with inflammatory skin diseases such as localized contact dermatitis and atopic dermatitis. However, one should not use these modalities to treat generalized itch. These antiinflammatory agents come in different strengths from mild to potent. As one moves up in the strength of the agent, there is a greater chance the agent will work but there is also a greater risk of side effects.
When it comes to corticosteroids, it is best to use them to bring an acute condition such as poison ivy or contact dermatitis under control or to treat minor local dermatoses like nummular or localized eczema. The side effects of long-term steroid use include atrophy of the skin, which may lead to skin fragility, telangiectasia, easy bruising and stretch marks.
Lidocaine 3% and hydrocortisone 0.5% (LidaMantle-HC®, Doak Dermatologics) in an acid mantle cream or lotion, provide a combination of a local anesthetic and a mild corticosteroid. This mixture is highly effective in treating the pruritus of localized conditions.
Topical immunomodulators inhibit T-lymphocyte activation. Accordingly, they reduce inflammation and ultimately decrease pruritus. Pimecrolimus cream (Elidel®, Novartis) and tacrolimus ointment (Protopic®, Astellas Pharma) preparations significantly reduce inflammation and pruritus in patients with moderate to severe atopic dermatitis with little resultant toxicity. Keep in mind that use of these agents over a wide area commonly causes a burning or stinging sensation on the first one or two applications. The role of these topical immunomodulators as an antipruritic for other pruritic conditions is not clear. One should reserve these for treatment of mild localized pruritus.
Other Topical Options That May Have An Impact
Low pH cleansers and moisturizers are useful in restoring and maintaining the acidic pH of the skin, which helps to preserve barrier function. The acidic skin surface is important in reducing skin irritation, which ultimately helps to reduce pruritus. Elevated skin surface pH has been noted in xerosis, atopic dermatitis and uremia.
Cooling agents are traditional, topical antipruritic over-the-counter preparations, which usually contain menthol, camphor or phenol. These substances stimulate the nerve fibers that transmit the sensation of cold, thereby masking the itching sensation. One can add these agents to aqueous cream to make a 1 to 2% compound cream, and the patient can apply the cream topically several times a day. All of the cooling agents are reasonably safe. However, applying large amounts of alcohol-containing preparations can cause stinging and can also irritate the skin.
Using wet wrap dressings for patients with refractory atopic dermatitis and localized eczema can reduce itching and promote healing. One may apply emollients or corticosteroid dilutions to the affected skin and then cover them with cool, occlusive, wet dressings. Patients may use ice to massage the area of intense pruritus to help bring it under control. The side effects are minimal and this treatment provides one more option for managing this disorder.