*2.3.3 Keratolytics*

Keratolytics (**Figure 4**) such as salicylic acid are readily used as active ingredients in many topical formulations, but may have particular utility when it comes to psoriasis as the disease is characterised by a build-up of keratinocytes on the skin. Keratolytics promote the physiologic skin shedding process and also decrease cell-tocell cohesion in the SC, in effect loosening the glue that keeps keratinocytes together [87, 99]. Salicylic acid has been shown to aid in the removal of excessive keratin in psoriatic plaques and to produce desquamation of the SC while being safe to use and not effecting qualitative or quantitative changes in the structure of the viable epidermis [100]. It is often used as either monotherapy or as part of combination therapy to reduce the size and scale of psoriatic plaques [15, 100]. Keratolytics have proven to be particularly effective in reducing psoriatic plaque thickness if prescribed several days prior starting a first-line treatment (i.e., corticosteroids) for localised psoriasis or in specific areas such as the scalp [87, 99].
