An evidence-based review of systemic treatments for itch

Many treatment modalities are used for itch treatment in daily medical practices without adequate evidence of their efficacy. The purpose of this study was to provide an evidence-based review of the literature as to the clinical benefits of systemic anti-itch treatments.

We performed a systematic review and, when appropriate, meta-analysis from available placebo-controlled randomized controlled trails (RCTs). A systematic search of the literature was performed using Pub Med, Cochrane Library and EMBASE. The primary outcome was the change in the itch score comparing the intervention group and placebo group. The meta-analysis method was used to calculate the pooled outcome of each treatment modality.

Twenty-six eligible RCTs were included. We found evidence for the effectiveness of: naltrexone (in cholestatic itch and atopic eczema), nalfurafine (in uraemic itch), gabapentin (in uraemic itch) and ursodeoxycholic acid (in intrahepatic cholestasis of pregnancy). The results of two RCTs with naltrexone in uremic itch are conflicting. On the other hand, we did not find any benefit from ondansetron (in cholestatic and uraemic itch), ergocalciferol (in uraemic itch), colesevelam (in cholestatic itch) or gabapentin (in cholestatic itch). The possible effectiveness of sertraline, paroxetine, cromolyn sodium, zinc sulphate, omega-3 fatty acid, montelukast, doxepin and rifampin need to be confirmed from future large studies, because the available evidence is insufficient.

The findings from this study suggest the effective therapeutic approaches for itch. The major limitations are that there are small numbers of available RCTs and methodological differences across studies.