Updated Meta-Analysis on Vitamin Supplementation for Chronic Pruritus: Expanding Evidence Beyond Vitamin D

Abstract

Chronic pruritus is a distressing condition associated with various dermatological and systemic diseases, significantly impairing patients' quality of life. While conventional treatments such as antihistamines and corticosteroids offer relief, their efficacy varies, and long-term use may lead to adverse effects. Emerging evidence suggests that certain vitamins, including vitamin D, vitamin E, vitamin B12, and niacinamide (B3), may play a role in alleviating pruritus through their anti-inflammatory, immune-regulatory, and skin barrier-enhancing properties. However, the effectiveness of these vitamins in managing chronic pruritus remains unclear. This meta-analysis aims to update and expand the evaluation of vitamin supplementation in reducing pruritus severity across different underlying conditions, extending the scope beyond vitamin D to include vitamins B and E. A comprehensive search was performed across PubMed, Embase, Web of Science, and Cochrane Library databases up to January 2025 to identify randomized controlled trials (RCTs) evaluating the effects of vitamin supplementation on chronic pruritus. A total of 21 RCTs (n = 1723) were included in the meta-analysis. Compared to placebo, vitamin supplementation demonstrated a significant reduction in pruritus severity (Standardized Mean Difference [SMD]: -0.578, 95% CI: -0.736 to -0.419, p = 0.000; I² = 53.630, p = 0.003). Subgroup analysis revealed that topical vitamin B12 and vitamin D3 showed the most pronounced antipruritic effects, particularly in patients with atopic dermatitis and chronic kidney disease-associated pruritus. Sensitivity analysis confirmed the robustness of the findings; however, potential publication bias was suggested by Egger's regression test (p = 0.00979), indicating that the overall effect may be influenced by small-study effects or underreporting of negative results. This meta-analysis indicates that vitamin B, D, and E supplementation may serve as effective adjunct therapies for managing chronic pruritus. However, the variability among the included studies highlights the necessity for well-structured, long-term RCTs to determine the ideal dosage, treatment duration, and target patient populations that would derive the greatest benefit from vitamin-based interventions.

Keywords: chronic non-communicable diseases; cytokine; health prevention; inflammation; niacinamide; vitamin.

Figure 1

A flowchart depicting the study selection process for the systematic review and meta-analysis on the effects of vitamin supplementation in managing chronic pruritus across various dermatological conditions. Out of 774 initially identified records, 21 studies met the eligibility criteria and were included in the final analysis.

Figure 2

Evaluation of the methodological quality of the included trials. (A) Individual risk of bias assessment for each selected study, based on the Rob 2.0 tool (https://mcguinlu.shinyapps.io/robvis/). (B) Overall risk of bias summarized as a percentage, considering intention-to-treat and per-protocol analyses. The primary sources of high risk of bias across the studies were deviations from intended interventions, followed by issues related to missing outcome data and deficiencies in the randomization process [7,8,9,10,11,12,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55].

Figure 3

Displays the overall impact of vitamins on chronic pruritus, as measured by the visual analog scale, compared to placebo [7,8,9,10,11,12,42,43,44,45,46,47,48,49,50,51,52,53,54,55].

Figure 4

A forest plot illustrating the subgroup analyses of vitamin supplementation in managing chronic pruritus. (A) Effect of treatment duration, (B) disease, (C) route of administration, and (D) different vitamin types. The squares represent the effect sizes, with horizontal lines indicating the 95% confidence intervals. The diamond symbol at the bottom of each panel summarizes the overall effect size.

Figure 5

A forest plot illustrating the combined effects of vitamin supplementation on chronic pruritus, integrating both the route of administration and vitamin type. The squares represent individual study effect sizes, with horizontal lines indicating 95% confidence intervals, while the diamond symbol at the bottom of each panel represents the overall pooled effect size.

Figure 6

A forest plot depicting the combined effects of vitamin supplementation on chronic pruritus, considering administration route, treatment duration, and vitamin type. The squares represent effect sizes of individual studies, with horizontal lines indicating 95% confidence intervals, while the diamond symbol at the bottom of each panel represents the overall pooled effect size.

Figure 7

Presents a forest plot that highlights the effects of vitamin supplementation. The plot is divided into four sections for ease of interpretation: (A) shows the effect on skin lesion area, (B) depicts changes in TNF levels, (C) assesses alterations in IL-6 levels, and (D) evaluates the impact on hs-CRP. The horizontal lines extending from the squares represent the 95% confidence intervals, while the diamond symbols indicate the overall effect sizes.

Figure 8

A sensitivity analysis evaluating the effects of vitamin supplementation on chronic pruritus, measured by the visual analog scale, compared to placebo following the exclusion of Jenssen (2023) [54]. The horizontal lines extending from the squares represent the 95% confidence intervals, while the diamond symbols indicate the overall effect sizes.

Figure 9

A funnel plot summarizing the findings from all included studies. The diagonal lines represent confidence intervals around the effect estimates, indicating the expected range for the true effect size. Each circle corresponds to an individual study, with larger circles reflecting studies with greater weight or larger sample sizes. The diamond symbol at the bottom represents the overall pooled effect size, with its center indicating the estimated effect and its width denoting the confidence interval.