The news of Chinese traditional medicines reaching Iran suggests that these medicines are becoming increasingly available internationally. Despite the long history of the toxic effects of mercury, mercury compounds are commonly used in Chinese traditional medicines. Two mercurials contained in some Chinese traditional medicines are the salts mercury(II) sulfide (HgS) and mercury(I) chloride (Hg₂Cl₂). Toxicological evidence from the past and principles of reactivity in inorganic chemistry are used to address the human health concern that is caused by Chinese traditional medicines in which either of the two mercury salts is present. The chemistry discussed in this article shows that the ingestion of HgS or Hg₂Cl₂ causes the introduction of aqueous mercury cations, especially Hg²⁺, into the human body. With that chemistry discussed and with the addressed toxic effects, science at the present time finds the Chinese traditional medicines that contain HgS or Hg₂Cl₂ disadvantageous compared to the antibiotics and sedatives that are available in modern medicine today.