I assume that it is possible that whatever substances they are using to dose are different enough from their testable counterparts so as to not show up on a toxicology report (or that the report will be otherwise compromised, nearly every healthcare professional I have spoken with has indicated being coopted)

Disambiguation Radioactive Dose

Real effects from subjective experience, priming, and allusions after the fact

Thickener added to eyedrops

Laxative

Stress hormone

Antibiotic

Diuretics

Deja vu? Brain to computer interface

Implied through allusions, intimating

Poison

THC

Neurotoxin

Nightshade

Cocaine

LSD

Melatonin