Intoxication (also known as substance intoxication), is a set of physiological and psychological conditions in an organism brought on by mind altering and/or psychotropic substances, such as alcohol and other recreational drugs of various kind. Exposure to an intoxicating substance usually occurs via ingestion of said substance, inhalation or dermal absorption.
Alcohol intoxication, also known as drunkenness, occurs when a person has had too much alcohol or ethanol in their bloodstream. The level of excess alcohol leads to physiological as well as psychological changes within an organisms which can range from mild to severe, depending on the amount of alcohol consumed and tolerance of the organism to the alcohol. Symptoms of alcohol intoxication include slurred speech, loss of balance, loss of muscle control, flushed skin, blood shot eyes, erratic behavior and loss of inhibition. Polywater is another intoxicating substance. (TOS: "The Naked Time"; TNG: "The Naked Now")
In 2364 nearly the entire crew of the USS Enterprise (NCC-1701-D) became intoxicated by polywater, resulting in everyone acting out of character and exhibiting severe mania with little to no inhibitions. Geordi La Forge, for example, became very emotional, crying that he wanted to have normal vision again, while Lieutenant Tasha Yar seduced an equally intoxicated Data. Wesley Crusher sealed off main engineering as part of an experiment and Doctor Beverly Crusher and Captain Jean-Luc Picard were close to crossing the line themselves, but luckily, she was able to find an antidote to combat the intoxication before the ship could be destroyed by everyone's reckless behavior. Captain Picard compared everyone's behavior to drunkenness. TNG: "The Naked Now")
In 2374, Steth, a shapeshifter with the ability to steal the DNA of any humanoid form, switched places with Tom Paris and posed as the real one on board USS Voyager. Seven of Nine caught him with flushed cheeks after he had replicated twelve alcoholic beverages through the replicator.
When in 2377, The Doctor hid his program in Seven's Borg implants, Seven, controlled by The Doctor, began consuming large amounts of alcohol and acted erratic, losing her inhibitions and otherwise Borg stoicism. Seven herself was not at all pleased with what The Doctor had done to her body, but The Doctor wanted to experience the sensation of being intoxicated with alcohol, among other things. (VOY: "Body and Soul")