Injection of oral medication into the skin confirmed by infrared spectroscopy

“Skin popping” refers to the practice of injecting drugs, most commonly heroin, subcutaneously or into granulation tissue. Pharmaceutical tablets meant for oral consumption are modified into solutions for injection. Excipients—inactive substances that serve as vehicles for medication—are often not filtered out before injection and result in abscess formation, granulomatous inflammation, and scarring. Common excipients used in the production of pharmaceutical tablets include starch, microcrystalline cellulose, magnesium stearate, silica, and polyvinylpyrrolidone (PVP). Identification of these exogenous materials is valuable in confirming the diagnosis of skin popping, especially when patients may not be forthcoming about their drug use. We present a case of subcutaneous oral medication injection in which PVP and cellulose were identified by Fourier transform infrared spectroscopy. Considering the variable cutaneous manifestations of injection drug abuse, recognition of histopathologic and chemical characteristics of exogenous material from oral medications is helpful for diagnosis and intervention.