Narcotic
Narcotics were naturally-occurring or synthetic drugs with psychoactive and highly intoxicating properties. Narcotics were often highly addictive and taking them resulted in changes in perception, mood, consciousness, cognition, and behavior. 

During the mid-21st century various Earth militaries controlled their soldiers through the use of drugs which produced a narcotic-like stupor. ()

Even though trellium-D, a deadly neurotoxin to Vulcans, was not a narcotic, it shared some similarities with narcotics. While gradually degrading the neural pathways of Vulcans, its immediate effects were in removing emotional inhibitions. Over time, use of trellium-D induced insanity and violent rages and the neurological damage became irreversible, eventually leading to death. () T'Pol suffered severe exposure to trellium-D while in an asteroid field and even though Doctor Phlox was able to reverse the neurological damage, T'Pol continued to hunger for the release from the constraints of logic the trellium had allowed. She developed a method of injecting it into her body and became addicted until, with Phlox's help, she successfully withdrew from the substance. However, her ability to control her emotions to a normal Vulcan level was permanently damaged. ()

In 2254 Vina described the Talosian's addiction to experiencing events in the thought record by comparing it to a narcotic. ()

The inhabitants of the failed Federation colony Turkana IV often turned to narcotics as an escape from the great poverty and violence that existed there. Natasha Yar described her knowledge of the effects of narcotic drugs, from experiences she witnessed on her homeworld, to her fellow crewmates, Data and Wesley Crusher in 2364; they did not understand why anyone "would voluntarily become dependent upon a chemical." ()

The Ornarans of planet Ornara suffered from an addiction to the narcotic created by the Brekkians known as felicium circa 2364. ()

In 2373, when the crew of the  docked at Bahrat's space station shortly before entering the Nekrit Expanse in the Delta Quadrant, Chakotay and Tom Paris were offered Rhuludian crystals for sale by a trader named Sutok. He explained that ingesting just one of the crystals would make days of tedious travel seem like moments of exquisite rapture. Chakotay and Paris immediately turned down his offer. ()

During the Occupation, Bajoran slave laborers on Terok Nor often partook of narcotic drugs, referred to as "chemicals". It was apparently common for users to be passed out on the Promenade, and for life-threatening disputes over them to arise. Users were often viewed with disgust by other Bajorans, believing that their undignified behavior justified the stereotypes Cardassians had of Bajorans, and the Resistance refused to smuggle them off the station. ()

Cadet-Captain Tim Watters also took narcotics over the course of his self-imposed mission during the Dominion War in order to deal with the pressure and stress of his duties. As such, many of his actions and command decisions were quite irrational. Also, under the influence of the drugs, Watters appeared to have developed the ego-maniacal impression that both he and his crew were "special" and fated to a great destiny. He also appeared to have developed faith in a higher power guiding his destiny, even broaching the opinion that Jake Sisko was guided to him by it to write his story. The extent to which Watter's actions and beliefs were due to the drugs, stress, or his own free choice to avoid returning to the Federation and remain in command was never made clear. ()

Ketracel-white, used by the Dominion to control Jem'Hadar soldiers in the 24th century, shared many of the same pharmacological traits as a narcotic. (, et al.; )

See also 
 Drug addict
 Felicium
 Ketracel-white
 Nitrogen narcosis
 Rhuludian crystals
 Temporal narcosis
 Trellium-D

External link 
 

de:Droge
Drugs