Nefarious substances in the US blood supply

Prescription and illicit drug is everpresent in the US, which can potentially result in controlled substances entering the US blood supply. Passive transfer of immune allergens is only anecdotally been reported as peanut allergens, fish allergens, and contrast material. However, US blood donors are only screened for a limited number of medications on the universal donor health questionnaire at time of collection. What, if any, effect does blood donor medication/drugs have on the recipients of these substances.