The number of new psychoactive substances (»NPS«) sold by online drug vendors (»Internet drugs«) shows a steady increase. Over a short time period in 2013-2014, three Swedish men aged 23-34 years with suspected drug use experienced similar but unusual clinical symptoms including loss and depigmentation of hair, widespread folliculitis and dermatitis, painful intertriginous dermatitis, dryness of eyes, and elevated liver enzymes. Two also had lines of discoloration across the nails (»Mees' lines«) of the fingers and toes. The symptoms gradually disappeared over time. However, two of them subsequently developed severe bilateral secondary cataracts requiring surgery. Blood tests for NPS performed within the Swedish STRIDA project demonstrated intake of the synthetic opioid MT-45, a piperazine derivative originally synthesized as a therapeutic drug candidate in the 1970s, in all three patients, suggesting this as a possible common causative agent. These clinical cases highlight the importance for physicians to consider the increasing number of untested recreational drugs as a potential cause of unusual clinical symptoms.