This investigation characterizes five surgical stainless steel piercings and one niobium piercing that caused adverse reactions during use, culminating with the removal of the jewelry. Chemical composition shows that none of the materials are in accordance with ISO standards for surgical implant materials. Additionally, none of the stainless steel piercings passed the pitting-resistance criterion of ISO 5832-1, which implies that [%Cr + 3.3(%Mo)] > 26. Under microscopic examination, most of the jewelry revealed the intense presence of linear irregularities on the surface. The lack of resistance to pitting corrosion associated with the poor surface finishing of the stainless steel jewelry may induce localized corrosion, promoting the release of cytotoxic metallic ions (such as Cr, Ni, and Mo) in the local tissue, which can promote several types of adverse effects in the human body, including allergic reactions. The adverse reaction to the niobium jewelry could not be directly associated with the liberation of niobium ions or the residual presence of cytotoxic elements such as Co, Ni, Mo, and Cr. The poor surface finish of the niobium jewelry seems to be the only variable of the material that may promote adverse reactions.