Types of Itch and the Itch-Scratch Cycle
Various types of itch have been described, including those related to skin disease, systemic disease, nerve fiber damage, and psychiatric or psychologic conditions. At any given time, patients may have pruritus caused by more than one of these sources. Certain types of itch may respond better than others to particular treatments. For example, pruritus related to dry skin will likely respond best to topical treatment with emollients. Itch related to a psychiatric condition, such as the delusion of parasitosis, will require oral therapy with an antipsychotic medication. Inflammatory skin diseases, such as atopic dermatitis, may respond best to a combination of oral and topical treatments.
Regardless of the underlying cause, itch evokes the behavior of scratching which increases inflammation and stimulates nerve fibers, leading to more itching and scratching (Hagermark & Wahlgren, 1995). Perpetuation of the itch-scratch cycle (see Figure 1) alters the integrity of skin leading to barrier damage. Scratching also causes undesirable changes in skin such as lichenification and prurigo nodule formation. Successful treatment of itch requires interruption of this cycle.
Itch-Scratch Cycle. Itch evokes the behavior of scratching which increases inflammation and causes excitation of nerve fibers, leading to more itching and scratching.
Dermatology Nursing. 2004;16(4) © 2004 Jannetti Publications, Inc.
Cite this: Practical Guidelines for the Relief of Itch - Medscape - Aug 01, 2004.