Current Topical and Systemic Therapies for Itch

Abstract

Itch is a common distressing symptom which may be caused by multifactorial aetiologies including inflammatory skin diseases, systemic diseases, neuropathic conditions and psychogenic disorders. Itch is a term used synonymously with pruritus and is defined as acute if it lasts less than 6 weeks or chronic if it persists for more than 6 weeks. It can have the same impact on the quality of life as chronic pain and shares many of the same pathophysiological pathways. Depending on the aetiology of the itch, different pathogenic mechanisms have been postulated with a number of mediators identified. These include histamine, leukotrienes, proteases, neuropeptides, cytokines and opioids, which may activate peripheral itch-mediating C-fibres via receptors on the nerve terminals and central neuronal pathways. Therefore, there is no single universally effective anti-itch treatment available. First-line treatments for itch include topical therapies, such as emollients, mild cleansers (low pH), topical anaesthetics, steroids, calcineurin inhibitors and coolants (menthol). Treatment with systemic therapies can vary according to the aetiology of the chronic itch. Non-sedating antihistamines are helpful in conditions such as urticaria where the itch is primarily histamine mediated. Although the itch of eczema is not mediated by histamine, sedating antihistamines at night are helpful to break the itch-scratch cycle. Chronic itch may also be treated with other systemic therapies, such as anticonvulsants, antidepressants as well as mu-opioid antagonists, kappa-opioid agonists and phototherapy, depending on the cause of the itch. This article summarises the topical and systemic therapies available with our current understanding of the pathophysiology of itch.

Inflammatory mediators causing cutaneous chronic itch in some diseases via transient receptor potential channel subfamily V member 1 and subfamily A member 1

“…52 We could pay more attention to the methods of curing chronic itch. However, the treatment of chronic itch has always been a big problem.…”

Study of Drug Utilization Pattern for Skin Diseases in Dermatology OPD of an Indian Tertiary Care Hospital - A Prescription Survey

“…This is expected as pruritus is one of the major complaints associated with majority of skin diseases and it is very troublesome and socially annoying to patient [23]. Antihistaminics are the mainstay for treatment of pruritus, and it is also prescribed other allergic conditions.…”

Protective effects of exogenous and endogenous hydrogen sulfide in mast cell-mediated pruritus and cutaneous acute inflammation in mice

“…According to the etiology, it may be acute or chronic (duration longer than 6 weeks), localized or generalized [1], [2]. A range of mediators, such as histamine [3], prostaglandins [4], serotonin [5], bradykinin [6], cytokines [7], endothelin-1 [8], leukotrienes [9], proteases [10,11], neuropeptides [12] and opioids [13] orchestrate this response by acting on their receptors located on the nerve terminals.…”

“…anaesthetics, antihistamines, steroids, calcineurin inhibitors and capsaicin cream) or systemic approach (e.g. antihistamines, antidepressants and immunossupressors) are normally prescribed according to the etiology [2].…”