text: Pseudoephedrine may be quantified in blood, plasma, or urine to monitor any possible performance-enhancing use by athletes, confirm a diagnosis of poisoning, or to assist in a medicolegal death investigation. Some commercial immunoassay screening tests directed at the amphetamines cross-react appreciably with pseudoephedrine, but chromatographic techniques can easily distinguish pseudoephedrine from other phenethylamine derivatives. Blood or plasma pseudoephedrine concentrations are typically in the 50–300 µg/L range in persons taking the drug therapeutically, 500–3000 µg/L in people with substance use disorder involving pseudoephedrine, or poisoned patients and 10–70 mg/L in cases of acute fatal overdose.