A<unk>  or<unk>  effect is an effect of a chemical substance, typically a medical drug, that is opposite to what would usually be expected. An example of a<unk>  is pain caused by a pain relief medication.<unk> s are more commonly observed in people with ADHD.
Paradoxical reaction
Ischemic cascade
Crepitation
Central tolerance
Abscopal effect
Neutral stimulus
Hypersensitivity
Parasympathetic rebound