Purpose of Review <p>Metal exposures are widespread, and ensuing allergic sensitization leads to secondary disease processes, especially contact dermatitis, with chronic implications. This review covers recently described mechanisms of sensitization, sources of exposure, and treatment options.</p> Recent Findings <p>Sensitization to metals is similar to other allergic processes: it is triggered by innate responses, which then facilitate allergic priming. Early oral exposures may lead to tolerance, whereas initial cutaneous exposures by piercings start the pathway toward sensitization. Nickel ‘allergy’ may be ubiquitous because of multiple pathways of immune response. Although the most frequent reaction to metals is a type IV immune response, some metals, including platinum and sometimes nickel, can also trigger a type I IgE mediated response. Current treatment involves avoidance of exposure and suppression of the response, although inducing tolerance by early oral exposure may be the best method to avoid disease.</p> Summary <p>Better understanding of the factors and contacts that drive metal sensitization will enable better management of the types and timing of exposure, which then may instead induce tolerance and prevent disease.</p>