Pruritus (synonymous with “itch”) can be defined as “an unpleasant sensation that provokes the desire to scratch” (Pfab et al. 2013). It is a common feature of many inflammatory skin diseases such as atopic dermatitis, irritant and allergic dermatitis, scabies, and lichen planus, but may also be seen in a large number of systemic conditions, including cholestasis, thyroid disorders, and kidney failure. Thus, it is important to determine the cause of the itch before attempting solely symptomatic treatment. Itch is classified as either acute (<6 weeks in duration) or chronic (>6 weeks in duration), and there is a significant psychosocial impact to pruritus that should not be overlooked (Callahan and Lio 2012). Beyond this, defining whether the itch is localized or generalized is also important for both diagnosis and therapy.

The pathophysiology of itch is nearly as diverse as its causes: there are both central and peripheral mechanisms involved, and a number of different pathways have been identified (Pfab et al. 2013). Conventional approaches to therapy—beyond treating the underlying disease when known—are somewhat lacking in clinical efficacy. These include topical agents such as corticosteroids, menthol, anesthetics, and capsaicin, as well as systemic agents such as antihistamines, antidepressants, and opioid antagonists (Yosipovitch and Bernhard 2013). It may be the somewhat limited efficacy of many of these treatments and/or their risk for significant side effects that drives interest in alternative agents.

See Table 15.1.

Stress is known to be a significant trigger for atopic dermatitis, and the itch-scratch cycle may become a deeply ingrained behavioral response that is elicited more during times of anxiety, regardless of the cause (Shenefelt 2003). It follows, then, that techniques to reduce stress could be helpful in the management of itch. Safe and somewhat holistic, hypnosis and cognitive behavioral techniques do seem to be helpful in both adults and children, and appear to have a durable response. Cost, time, and availability of such treatments can present barriers for utilizing these modalities.