CD25 Eczema flares mediated by oral exposure to nickel

Abstract Nickel systemic contact dermatitis (SCD) occurs when a person who is presensitized to nickel is exposed to it via a systemic route, including oral consumption, causing dermatitis. Many foods are known to have a natural high nickel content, but it is unclear whether dermatologists should advise their sensitized patients with eczema to avoid nickel-rich food to prevent eczematous flare-ups. We set out to examine the evidence for the role of dietary intervention to reduce nickel consumption as a management strategy in patients with eczema who patch test positive to nickel. We undertook a systematic review of the Web of Science, MEDLINE and Embase databases from 2017 to 2025. Randomized clinical trials, prospective trials and case series were included, and the systematic review was registered on PROSPERO. The search included studies of patients with eczema with a history of nickel allergy evidenced by a prior positive nickel patch test who then underwent nickel oral challenge or dietary exclusion. There was no restriction on age, ethnic background or other notable demographics. Non-English studies and animal studies were excluded. These data were supplemented by our previous systematic search results from inception to 2017. The database searches identified 7114 studies, of which 32 met the inclusion and exclusion criteria. Evidence quality was graded as per the GRADE criteria. Six randomized controlled trials (collectively n = 258) showed that 52.6% of patients had eczema flares following nickel challenge (18% with placebo). Eleven prospective controlled studies (collectively n = 552) showed a positive association between nickel exposure and persistent eczema in 54% of cases. The majority of the other studies showed evidence for the benefit of oral nickel avoidance in sensitized patients. The interpretation of this review is limited by the heterogeneous study methodologies, poorly described randomization processes and varied primary outcomes. In our estimation, the evidence suggests that approximately 50% of those sensitized to nickel with poorly controlled eczema and nickel allergy may benefit from a low-nickel diet. Despite the uncertainty of the evidence, low-nickel diets offer a low-risk treatment option for patients with severe eczema who might not have responded to multiple systemic treatments or had significant complications from prior treatments. We suggest that this low-cost intervention should be considered in those with eczema who have a positive nickel patch test or a strong clinical suspicion of nickel sensitization. There is still a need for larger, randomized studies that can better elucidate this effect and identify the patient subgroup that will benefit the most.