Drugs leading to hyperreflexia or muscle irritability are often those that may cause seizures:
However, if there is compromise of CNS perfusion, then seizures may occur with any of these drugs.
Myoclonic jerking (without fitting) is suggestive of the serotonergic syndrome.
Hyperadrenergic states (withdrawal states, sympathomimetic drugs) and the serotonergic syndrome are associated with hyperreflexia. In serotonin toxicity, the hyperreflexia is typically confined to the lower limbs.
Serotonin reuptake inhibitors can cause prominent myoclonus and tremor that may be confused with seizures. Hyperreflexia from SSRIs is often confined to the lower limbs.