Intravenous narcotic, so named because it stimulates the nervous system and provides a shot of adrenaline to the user, Rush is considered a controlled substance, though enforcing the ban on its use has proven difficult. It is said to provide a calming sense of euphoria, followed by a powerful burst of energy. In small doses long-haul starship pilots, college students, and stellar traffic controllers among others use it to stay alert.

Casual users tend to use an aerosol form of the drug and inhale it, absorbing it through their olfactory blood vessels. For addicts, a liquid form of the drug may be injected into the vein with a hypo-gun, or injected under the eyes with a special ocular injector. Continued used of ocular injectors irritates the soft tissues under the eyelids, leading to a condition commonly referred to as "bloody tears."