We report the severe mercury poisoning of a 4-year-old child by a so far unknown route of exposure, namely, by skin-to-skin contact. The child was admitted to the hospital with episodic pain in his extremities, tachycardia, hypertension, increased sweating, behavioral changes and weight loss. Extensive examinations eventually revealed an acute mercury poisoning. The initial mercury levels were 19 µg/L in urine (reference level 0.4 µg/L) and 37 µg/L in blood (reference level 0.8 µg/L). A facial cream bought online, containing approximately 18% mercury, was identified as the primary source of intoxication. The symptoms improved after disposal of the cream and chelation therapy. Further analyses, home visits and interviews suggested that the child was accidently intoxicated by skin-to-skin contact with the mother, although other routes of exposure such as dust ingestion and surface-to-skin contact cannot be excluded. The mercury levels in urine and blood samples of the child and other family members as well as in domestic dust samples decreased considerably over time.