Hair dyes are substances commonly used by the general population. Although their composition varies depending on the manufacturer, the following compounds have the greatest potential for toxicity: ammonium, hydrogen peroxide, and oxidizing substances such as paraphenylenediamine. Exposure to these substances could be accidental, occupational, or self-induced. Unfortunately, this information is often unknown to the clinical practitioners, making it difficult to diagnose and properly treat patients under this kind of intoxication in the emergency room. In this paper, we present two cases with different outcomes in which the patients were exposed (either accidentally or self-induced) to hair dye containing paraphenylenediamine, one of the substances that explains the metabolic, cardiovascular, and kidney compromise associated to this intoxication.