Encaprin was soon embroiled in the product tampering scares following the 1982 Chicago Tylenol murders . On 27 March 1986 , an anonymous caller phoned Procter & Gamble claiming he had placed cyanide in capsules of maximum strength Encaprin in Walgreens pharmacies in Chicago and Detroit , leading Walgreens , Kroger supermarkets and SupeRx drug stores to remove the product from all stores nationally . The manufacturer issued a recall and advisory cautions were announced , although many initially suspected the call was a hoax , particularly because there were no Walgreens locations in Detroit at the time . On 5 April 1986 , Procter & Gamble announced that no evidence of tampering had been found , and Encaprin was returned to the shelves . Despite the fact that the scare was revealed to be a hoax , Encaprin never recovered its sales and was quietly retired in August 1986
Chicago Tylenol murders
Chicago Tylenol murders
Encaprin